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Keithley 2750 User Manual

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Model 2750

Multimeter/Switch System

User's Manual

2750-900-01 Rev. F / August 2011

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Summary of Contents for Keithley 2750

Page 1 Model 2750 Multimeter/Switch System User’s Manual 2750-900-01 Rev. F / August 2011...
Page 2 Model 2750 Multimeter/Switch System User’s Manual 2011, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A. Document Number: 2750-900-01 Rev. F...
Page 4: Safety Precautions
Service personnel are trained to work on live circuits, perform safe installations, and repair products. Only properly trained service personnel may perform installation and service procedures. Keithley Instruments products are designed for use with electrical signals that are rated Measurement Category I and Measurement Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664.
Page 5 themselves from the risk of electric shock. If the circuit is capable of operating at or above 1000V, no conductive part of the circuit may be exposed. Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance- limited sources.
Page 6 (note that selected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product). If you are unsure about the applicability of a replacement component, call a Keithley Instruments office for information.
Page 8: Table Of Contents
General information ................. Contact information ................Safety symbols and terms ..............Inspection ..................Options and accessories ..............Model 2750 features ................. Plug-in switching modules ............... Pseudocards ..................Identifying installed switching modules ........... Front and rear panel familiarization ............Front panel summary ................
Page 9 2-wire functions ................. 4-wire functions (paired channels) ............ Controlling the system channel ............Non-amp and non-measure switching modules ......2-13 Multiple channel operation ..............2-15 Controlling multiple channels ............2-17 Multiple channel operation anomalies ..........2-21 Dual independent multiplexers ............2-23 Identifying installed modules and viewing closed channels ....
Page 10 Thermistors ..................3-27 4-wire RTDs ..................3-28 Connections ..................3-28 Temperature measurement configuration ........3-34 Temperature measurement procedure ..........3-37 Frequency and period measurements ............. 3-38 Trigger level ..................3-38 Gate time ..................3-38 Connections ..................3-39 Frequency and period measurement procedure ......3-40 Continuity testing ...................
Page 11 Relative ..................... Basic operation .................. Remote programming — rel ............. Math ......................mX+b ....................Percent ..................... 5-10 Reciprocal (1/X) ................5-11 Basic operation ................5-12 Remote programming — math ............5-13 Ratio and channel average ..............5-16 Basic operation ................5-17 Remote programming —...
Page 12 Manual/external trigger scan ............7-22 Monitor scan (analog trigger) ............7-23 Remote programming — scanning ............7-25 Trigger model .................. 7-25 Channel setup .................. 7-26 Buffer ....................7-26 Scanning commands ............... 7-26 Scanning programming example ............ 7-31 Scanning examples ................. 7-32 External trigger scan ...............
Page 13 Limits ....................9-16 Digital outputs ................. 9-18 Remote Operations Operation enhancements ................ 10-2 Pseudocards ..................10-2 Autozero ..................10-2 dB calculation .................. 10-2 Separate function setups ..............10-3 DCV input divider ................10-3 Multiple channel operation .............. 10-3 GPIB setup ....................10-4 GPIB standards ................
Page 14 Error messages ................10-21 Status Structure Overview ....................11-2 Status byte and SRQ ............... 11-2 Status register sets ................11-2 Queues .................... 11-2 Clearing registers and queues ..............11-4 Programming and reading registers ............11-5 Programming enable registers ............11-5 Reading registers ................
Page 15 SYSTem:BEEPer[:STATe] <b> ............. 14-8 SCPI Reference Tables Reference tables ..................15-2 Model 7700 Connection Guide Card configuration — schematic ............. Connections and wiring ................Screw terminals ................Wiring procedure ................Typical connections ................Connection log ................B-10 Status and Error Messages Signal Processing Sequence and Data Flow Signal processing sequence ..............
Page 16 Source resistance noise ..............Magnetic fields .................. Radio frequency interference ............Ground loops ..................Shielding ................... Meter loading .................. E-10 Temperature Equations Thermocouple equation ................Thermistor equation ................. RTD equation ................... IEEE-488 Bus Overview Introduction ....................Bus description ..................Bus lines ....................Data lines ..................
Page 18: Getting Started
Front and rear panel familiarization — Summarizes the controls and connectors of the instrument. • Rack mounting — Covers the options available for rack mounting the Model 2750 in a standard 19-inch rack. QS2 • Power-up — Covers line power connection, line voltage setting, fuse replacement, power line frequency, and the power-up sequence.
Page 19: General Information
Contact information Worldwide phone numbers are listed at the front of this manual. If you have any questions, please contact your local Keithley representative or call a Keithley Application Engineer at 1-800-348-3735 (U.S. and Canada only). Safety symbols and terms...
Page 20: Inspection
Getting Started Inspection Model 2750 was carefully inspected electrically and mechanically before shipment. After unpacking all items from the shipping carton, check for any obvious signs of physical damage that may have occurred during transit. (There may be a protective film over the display lens, which can be removed).
Page 21 Models 7701, 7707 and 7709 switching modules. Cables and adapters (GPIB and trigger link) Models 7007-1 and 7007-2 shielded GPIB cables — Connect Model 2750 to the GPIB bus using shielded cables and connectors to reduce electromagnetic interference (EMI). Model 7007-1 is one meter long; Model 7007-2 is two meters long.
Page 22: Model 2750 Features
Model 2750 Multimeter/Switch System User’s Manual Getting Started Rack mount kit Model 4288-7 rack mount kit — Mounts a Model 2750 in a standard 19-inch rack. Includes rear brackets to provide additional support for a mainframe that has two or more switching modules installed.
Page 23: Plug-In Switching Modules
The digital trigger link and hardware interlock input can also be accessed at this port. • Monitor — The Model 2750 can monitor a selected channel. A scan can be trig- gered to start when the Monitor detects a reached reading limit. •...
Page 24 1 and totalizer 2 connect to 1. Latching relays hold their open/close state after the Model 2750 is turned off. When turned on, all relays open after a few seconds. 2. All multiplexers can be configured as two independent multiplexers.
Page 25: Pseudocards
With a pseudocard “installed,” the Model 2750 will operate as if the switching mod- ule is installed in the Model 2750. This feature allows you to configure your system with- out having the actual switching module installed in the unit. There is a pseudocard for every Keithley Model 77XX series switching module.
Page 26: Front And Rear Panel Familiarization
Use to select a shifted function or operation. LOCAL Cancels GPIB remote mode. POWER Power switch. In position turns 2750 on (I), out position turns it off (O). 2 Function and operation keys: Top Row Unshifted Selects DC voltage measurement function.
Page 27 Restores a default setup (factory or *RST) or a saved setup. Enables/disables buffer auto clear, auto scan, and auto channel configuration. Sets timestamp, date, and time. Displays serial number of Model 2750. CONFIG Selects and configures a simple scan or an advanced scan.
Page 28 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-11 4 Display annunciators: * (asterisk) Readings being stored in buffer. ↔ (more) Indicates additional selections are available. ))) (speaker) Beeper on for continuity or limits testing. Digital input/output or analog output active (set to non-default value).
Page 29: Rear Panel Summary
6 Slots 1 through 5 Five slots to accommodate Keithley Model 77XX series switching modules. The Model 2750 is shipped from the factory with slot covers installed. Please note additional slot covers can be requested from Kei-...
Page 30: Rack Mounting
Getting Started 1-13 Rack mounting The Model 2750 can be mounted in a standard 19-inch rack. For a mainframe that has one or no switching modules installed, the Model 2750 can be secured to the front rails of the rack.
Page 31: Power-Up
Model 2750 Multimeter/Switch System User’s Manual Power-up Line power connection Follow the procedure below to connect the Model 2750 to line power and turn on the instrument. Check to see that the line voltage indicated in the window of the fuse holder assem- (Figure 1-4) is correct for the operating voltage in your area.
Page 32: Line Frequency
1-15 Line frequency The Model 2750 will operate at line frequencies from 45Hz to 66Hz, and 360Hz to 440Hz. There are no user-settings for line frequency. It is automatically sensed at power-up. The following command can be used to read the line frequency: SYSTem:LFRequency? ' Query power line frequency.
Page 33: Power-Up Sequence
Model 2750 Multimeter/Switch System User’s Manual Power-up sequence On power-up, the Model 2750 performs self-tests on its EPROM and RAM and momen- tarily lights all segments and annunciators. If a failure is detected, the instrument momen- tarily displays an error message and the ERR annunciator turns on. (Error messages are...
Page 34: Display
Appendix Remote programming — display Using remote programming, the Model 2750 can display a custom ASCII message (up to 12 characters). Also, the front panel display and controls can be disabled. Display commands The commands are listed in Table 1-3.
Page 35 1-18 Getting Started Model 2750 Multimeter/Switch System User’s Manual DISPlay:TEXT:DATA <a> Define text message This command defines the text message for display. A message can be as long as 12 char- acters. A space counts as a character. Excess message characters results in an error. The characters must be enclosed in either single quotes (‘...
Page 36: Defaults And User Setups
1-19 Defaults and user setups Model 2750 can be restored to one of two default setup configurations (FACTory or *RST), or three user-saved (SAV0, SAV1, or SAV2). As shipped from the factory, Model 2750 powers up to the factory (FACT) default settings.
Page 37: Saving And Restoring Setups
If the settings for a user setup or power-on setup do not match the switching module types presently installed in the Model 2750, error +520 (Saved setup scancard mismatch) occurs when the setup is recalled. The scan list will reset to the factory defaults and all channels will open.
Page 38 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-21 Table 1-4 Default settings Setting Factory *RST Set Diff Auto channel configuration No (off) No effect Autozero Buffer No effect No effect Auto clear Yes (on) No effect Channel Average Closed channels...
Page 39 1-22 Getting Started Model 2750 Multimeter/Switch System User’s Manual Table 1-4 (continued) Default settings Setting Factory *RST Set Diff Limits LO Limit 1 HI Limit 1 LO Limit 2 HI Limit 2 Line Synchronization Math mX+B Scale Factor Offset Units “X”...
Page 40 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-23 Table 1-4 (continued) Default settings Setting Factory *RST Set Diff RS-232 Baud rate No effect No effect Flow control XonXoFF XonXoFF Terminator No effect No effect Scanning Disabled Disabled Auto scan...
Page 41: Remote Programming - Default And User Setups
1-24 Getting Started Model 2750 Multimeter/Switch System User’s Manual Table 1-4 (continued) Default settings Setting Factory *RST Set Diff Voltage (AC and DC) Reference Digits (AC) 5H digits 5H digits Digits (DC) 6H digits 6H digits Filter Window 0.1% 0.1%...
Page 42: Remote Programming Information
(?) that follows the command word. A query command requests (queries) the programmed status of that command. When a query command is sent and Model 2750 is addressed to talk, the response message is sent to the computer. NOTE For complete details, see “Programming syntax,”...
Page 43: Basic Dmm Measurements - Front Panel Inputs
Section 3 for details on basic DMM operation. The Model 2750 is shipped from the factory to power-up to factory defaults. The instru- ment powers up to a setup that continuously measures DC volts. Some of the default set- tings for the DCV function include auto range enabled, 6½-digit resolution, filter enabled, and slow reading rate.
Page 44 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-27 The following examples demonstrate how to include the function name in the command string for configuration commands. VOLT:RANG 10 Select 10V range for DCV. RES:RANG:AUTO ON Enable auto range for W2.
Page 45: Closing And Opening Channels - System Channel Operation
1-28 Getting Started Model 2750 Multimeter/Switch System User’s Manual Closing and opening channels — system channel operation NOTE Section 2 for details on closing and opening switching module channels. NOTE The following discussion assumes a multiplexing switching module (i.e., Model 7700) installed in slot 1 of the mainframe.
Page 46 When a system channel is closed, the channel number will be displayed on the Model 2750. The slot number for the module is also displayed. For example, “103” indicates that system input channel 3 for a module in slot 1 is closed.
Page 47 1-30 Getting Started Model 2750 Multimeter/Switch System User’s Manual Figure 1-7 Front panel keys to close and open system channels Close next measurement channel Press OPEN key Press CLOSE key OPEN CLOSE OPEN CLOSE Display ALL Display SINGLE option CLOSE:SINGLE...
Page 48: Simple Scanning
Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-31 Exercise 2 — Closing and opening channels (system channel operation) The exercise in Table 1-7 demonstrates a sequence to close and open channels of a Model 7700 installed in slot 1 of the mainframe.
Page 49 NOTE The Model 2750 can also be configured to run an advanced scan. For an advanced scan, each channel can have its own unique setup (i.e., function, range, etc.). Advanced scanning is covered in...
Page 50 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-33 For remote programming, the following commands are used for simple scanning: ROUTe:SCAN <clist> Define scan list*. TRIGger:COUNt <NRf> Specify number of scans (1 to 11000 or INFinity). SAMPle:COUNt <NRf> Specify number of channels to scan ' (1 to 11000).
Page 51: Trigger And Return Readings - Remote Programming
1-34 Getting Started Model 2750 Multimeter/Switch System User’s Manual Trigger and return readings — remote programming There are several commands used to trigger and return readings. The proper commands and sequence to use depend on trigger state (continuous or non-continuous) and what you are trying to accomplish.
Page 52 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-35 Figure 1-9 Exercise 4 — Trigger and return a single reading Place 2750 in INIT:CONT OFF non-continuous TRIG:COUN 1 trigger state Trigger Configuration Set 2750 to perform SAMP:COUN 1 one measurement...
Page 53 1-36 Getting Started Model 2750 Multimeter/Switch System User’s Manual Figure 1-10 Exercise 5 — Trigger and return multiple readings TRAC:CLE Clear Buffer Place 2750 in non-continuous INIT:CONT OFF trigger state TRIG:COUN 1 Trigger Configuration Set 2750 to perform “x” SAMP:COUN x...
Page 54 Model 2750 Multimeter/Switch System User’s Manual Getting Started 1-37 Figure 1-11 Exercise 6 — Return a single reading (continuous triggering) Place 2750 in SAMP:COUN 1 continuous Trigger Configuration INIT:CONT ON trigger state. FETCh? DATA? Return Readings CALC:DATA? DATA:FRESh? 2, 3...
Page 55 1-38 Getting Started Model 2750 Multimeter/Switch System User’s Manual...
Page 56: Closing And Opening Switching Module Channels
• Switching module installation and connections — Explains how to install a switching module (or pseudocard) into the Model 2750 mainframe. Also explains where to find connection information which should only be performed by qualified service personnel.
Page 57: Close/Open Overview
NOTE The Model 2750 can scan switching module channels. Each channel in the scan can have its own unique setup configuration. Scanning is covered in Section...
Page 58: Switching Module Installation And Connections
Perform the following steps to install a switching module into the Model 2750 mainframe: Turn the Model 2750 off and disconnect the power line cord and any other cable connected to the rear panel. Position the Model 2750 so you are facing the rear panel.
Page 59: Connections
• Before making or breaking connections to the switching module, make sure the Model 2750 is turned off and power is removed from all external circuitry. • Do not connect signals that will exceed the maximum specifica- tions of switching module.
Page 60: Pseudocards
There is a pseudocard for every Keithley Model 77XX series switching module. A pseudocard cannot be installed from the front panel. However, once it is installed, you can take the Model 2750 out of remote and use the front panel. Pressing the LOCAL key takes the Model 2750 out of remote.
Page 61: System Channel Operation
DMM Input of the Model 2750. The system channel number is displayed on the Model 2750. For a 4-wire function (i.e., Ω4), the paired channel for the system channel is internally connected to DMM Sense. The paired channel is not displayed on the Model 2750.
Page 62: 2-Wire Functions
DMM Input of the Model 2750. Assume a Model 7700 switching module is installed in slot 1 of the mainframe. When channel 101 is closed using the system channel close keys, both the Channel 1 relay and the backplane isolation relay (Channel 25) closes to connect the chan- nel to the DMM.
Page 63: Controlling The System Channel
Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual Figure 2-2 4-wire system channel connections to Model 2750 DMM Model 2750 Slot 1 Model 7700 Switching Module Channel 1 Relay Channel 25 Channel 1 Input Backplane Isolation Relay System Channel Operation:...
Page 64 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels NOTE keys can also be used to open all channels in the mainframe. Sim- ply increment or decrement the channel number until there is no channel dis- played. Figure 2-3 System channel operation —...
Page 65 2-10 Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual TOO SMALL or TOO LARGE — These messages also indicate an invalid channel. TOO SMALL indicates that the specified channel and any other lower numbered channel is invalid. TOO LARGE indicates that the specified channel and any other higher numbered channel is invalid.
Page 66 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-11 Remote programming — system channel control commands The commands to close and open the system channel are listed in Table 2-1. When a sys- tem channel reading is returned, the system channel number will be included in the data string if the CHANnel data element is selected.
Page 67: Non-Amp And Non-Measure Switching Modules
The following example assumes a Model 7700 installed in slot 1, and the Ω4 function of the Model 2750 is selected. This command sequence connects channel 101 and its paired channel (111) to DMM Input and Sense as shown in Figure 2-2.
Page 68 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-13 If a system channel is already closed and you attempt to select the DCI or ACI function, the message “INVALID FUNC” will be displayed briefly. For remote programming, error -221 (Settings conflict) is generated. Example: SYST:PRES ' Restores system preset defaults.
Page 69: Multiple Channel Operation
Non-measure switching modules NOTE Presently, non-measure Keithley modules include the Models 7705, 7711, and 7712. You can check the Keithley website (www.keithley.com) for new modules. Keep the following in mind when using a non-measure module: • For a non-measure card, no channels are connected to the internal DMM (the channels cannot be connected to the backplane).
Page 70 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-15 isolation channels. Multiple channel operation should only be performed by experienced test system engineers. WARNING Careless multiple channel operation could create an electric shock haz- ard that could result in severe injury or death. Improper operation can also cause damage to the switching modules and external circuitry.
Page 71: Controlling Multiple Channels
• A channel closed using multiple channel operation is not displayed on the Model 2750. Also, the CHAN annunciator does not turn on when a channel is closed. • Opening a channel using multiple channel operation has no affect on other closed channels.
Page 72 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-17 CLOSE key (MULTI menu option) The MULTI menu option for the CLOSE key can be used to close any individual channel in the mainframe (Figure 2-6). Perform the following steps to close a channel: NOTE Channels closed by the MULTI option of the CLOSE key are not displayed.
Page 73 Press ENTER to open the channel. NOTE If the channel you open using OPEN: MULTI is the system channel (channel number displayed on the Model 2750), the channel will open, but the system channel number will still be displayed (see “Multiple channel operation anomalies,”...
Page 74 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-19 Reference: ROUTe:MULTiple:CLOSe <clist> This command functions like the front panel CLOSE key (MULTI menu option) to close channels. When you send this command to close the channels specified in the <clist>, only those listed channels will close.
Page 75: Multiple Channel Operation Anomalies
Use the MULTI option for the OPEN key, open channel 101. Even though channel 101 is still being displayed on the Model 2750, it is channel 102 that is actually connected to the DMM Input (channels 102 and 125 closed).
Page 76 Channel 124 (connects channel 111 to DMM Sense). • Channel 123 (isolates channel 101 from channel 111). The Model 2750 will display the 1kΩ reading for system channel 101. Remote programming: ROUT:CLOS (@101) Using the MULTI option for the OPEN key, open channel 111. This opens the con- nection to DMM Sense and causes an OVRFLW reading.
Page 77: Dual Independent Multiplexers
11 through 20). For the dual multiplexer configuration, only Multiplexer A channels can be internally con- nected to the DMM of the Model 2750. For the Model 7700, closing channel 25 allows channels 1 through 10 to be measured by the DMM.
Page 78 This application demonstrates how to use the Model 7700 as a dual multiplexer to bias and measure 10 DUT. An external source powers the DUT, while the DMM of the Model 2750 measures the output of the DUT. To prevent overloading of the external source, each DUT is powered (and measured) separately.
Page 79 2-24 Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual Figure 2-9 Dual multiplexer application connections Model 2750 Model 7700 Switching Module External Sense Source Ch 1 Ch 2 Ch 10 Input Ch 25 Ch 23 (Closed) Ch 11...
Page 80 Open all channels. For most switching modules, channels remain closed after the Model 2750 is turned off. Therefore, it is good, safe practice to open all channels at the start and end of the test. Front panel operation: Press OPEN > Display ALL > Press OPEN...
Page 81 2-26 Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual Test the remaining eight DUT in a similar manner. That is, close the appropriate channels for the DUT, make the measurement, and then open the channels. After the last DUT is tested, repeat step 1 to open all channels.
Page 82: Identifying Installed Modules And Viewing Closed Channels
If a Model 7700, 7701, 7702, 7703, 7705, 7708, or 7709 switching module is removed while the Model 2750 is on, the slot indicator for that slot will remain on, and the instrument will operate as if the module is installed. That is, the Model 2750 will operate as if the pseudocard is installed.
Page 83 2-28 Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual CARD: CONFIG — This menu item is used to configure switching modules. The chan- nels of the Model 7700 switching module and other similar type modules do not need to be configured.
Page 84: Switching Module Queries (Remote Operation)
For remote operation, the *OPT? command can be used to determine which switching modules (or pseudocards) are installed in the Model 2750. For example, assume a Model 7700 is installed in slot 1, a Model 7706 is installed in slot 2 and the other slots are empty.
Page 85 SYSTem:CARD commands There is a series of SYSTem:CARD commands that can be used to acquire the following information about a switching module installed in the Model 2750: • Return the serial number and firmware revision. •...
Page 86: Relay Closure Count
2-31 Relay closure count The Model 2750 keeps an internal count of the number of times each module relay has been closed. The total number of relay closures are stored in EEPROM on the card. This count will help you determine if and when any relays require replacement (see module contact life specifications).
Page 87: Reading Relay Closure Count
NOTE If the Model 2750 is turned off before the updated count is written to EEPROM, the relay counts will be lost. It is good practice to add the ROUT:CLOS:COUN? <clist>...
Page 88: Model 7700 Switching Module
When the Model 2750 is on the DCV, ACV, Ω2, CONT, Ω4, FREQ, PERIOD, or TEMP function, channels 1 through 20 are available. When on a current function (DCI or ACI), channels 21 and 22 are the only available channels.
Page 89: Schematic Diagram
There are two backplane relays (channels 24 and 25) to connect the input channel(s) to the backplane of the Model 2750. With a 2-wire function (except amps) selected, channel 25 will close, and with a 4-wire function selected, both channels 24 and 25 will close.
Page 90 Model 2750 Multimeter/Switch System User’s Manual Close/Open Switching Module Channels 2-35 Figure 2-12 Model 7700 simplified schematic Input Sense HI Cold Junction Ref x3 Channel 1 Channel 25 (See Note) (Channels 2–9) Backplane Isolation Channel 10 Input Channel 23 2-Pole (Open)
Page 91 2-36 Close/Open Switching Module Channels Model 2750 Multimeter/Switch System User’s Manual...
Page 92: Basic Dmm Operation
Basic DMM Operation • DMM measurement capabilities — Summarizes the measurement capabilities of the Model 2750 and covers maximum signal levels for switching modules. • High energy circuit safety precautions — Provides safety information when per- forming measurements in high energy circuits.
Page 93: Dmm Measurement Capabilities
For the other switching modules, the maximum signal levels are included with their specifications. NOTE This section shows DUT connections to the front panel inputs of the Model 2750 and to the Model 7700 switching module. Details on Model 7700 connections are provided in...
Page 94: High Energy Circuit Safety Precautions
As described in the International Electrotechnical Commission (IEC) Standard IEC 664, the Model 2750 is Installation Category I and signal lines must not be directly connected to AC mains. When making measurements in high energy circuits, use test leads that meet the following requirements: •...
Page 95: Performance Considerations
Performance considerations Warm-up After the Model 2750 is turned on, it must be allowed to warm up for at least two hours to allow the internal temperature to stabilize. If the instrument has been exposed to extreme temperatures, allow extra warm-up time.
Page 96: Lsync (Line Cycle Synchronization)
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation LSYNC (line cycle synchronization) Synchronizing A/D conversions with the frequency of the power line increases common mode and normal mode noise rejection. When line cycle synchronization is enabled, the measurement is initiated at the first positive-going zero crossing of the power line cycle after the trigger.
Page 97: Remote Programming - Autozero And Lsync
Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Remote programming autozero and LSYNC — Autozero and LSYNC commands The commands to control display resolution (digits) are listed in Table 3-1. Table 3-1 Autozero and LSYNC commands Commands Description Default Autozero command* SYSTem:AZERo:STATe <b>...
Page 98: Channel List Parameter ()
Basic DMM Operation Channel list parameter (<clist>) Channels of one or more switching modules installed in the Model 2750 can be scanned. Each scan channel can have its own unique setup. For example, a channel could be set to measure DCV on the 10V range, while another channel can be set to measure ACV on the 1V range.
Page 99: Voltage Measurements (Dcv And Acv)
Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Voltage measurements (DCV and ACV) The Model 2750 can make DCV measurements from 0.1µV to 1000V and ACV measure- ments from 0.1µV to 750V RMS, 1000V peak. DCV input resistance: 100V and 1000V ranges: 10MΩ...
Page 100 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation Front panel input When using the front panel input terminals, connect the test leads to the INPUT HI and LO terminals as shown in Figure 3-2. Figure 3-2 DCV and ACV connections using front panel inputs...
Page 101 3-10 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Model 7700 switching module Connections for the Model 7700 switching module are shown in Figure 3-3. For basic DCV and ACV measurements (Figure 3-3A and B), channels 1 through 20 can be used.
Page 102: Volts Measurement Procedure
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-11 Volts measurement procedure NOTE Make sure the INPUTS switch is in the correct position. To use front panel inputs, it must be in the “F” (out) position. For switching modules, it must be in the “R”...
Page 103: Crest Factor
Therefore, to minimize AC interference, the circuit should be shielded with the shield connected to the Model 2750 input low (particularly for low level sources). Improper shielding can cause the Model 2750 to behave in one or more of the following ways: •...
Page 104 The REL control can be used to null out constant offset voltages. AC voltage offset The Model 2750, at 5H digits resolution, will typically display 100 counts of offset on AC volts with the input shorted. This offset is caused by the offset of the TRMS converter.
Page 105: Current Measurements (Dci And Aci)
Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Current measurements (DCI and ACI) The Model 2750 can make DCI measurements from 10nA to 3A and ACI measurements from 1µA to 3A RMS. NOTE See the previous discussion about crest factor in “Voltage measurements (DCV...
Page 106: Amps Measurement Procedure
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-15 Model 7700 switching module Connections for the Model 7700 switching module are shown in Figure 3-5. Note that only channels 21 and 22 can be used for current measurements. Figure 3-5...
Page 107: Amps Fuse Replacement (Front Panel Amps Input)
Manual for fuse replacement information. Resistance measurements (Ω2 and Ω4) The Model 2750 uses the constant-current method to measure resistance from 1Ω to 1MΩ . The Model 2750 sources a constant current (I) to the resistance and measures the voltage (V).
Page 108: Connections
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-17 Connections NOTE When using the front panel inputs, the INPUTS switch must be in the “F” (out) position. For switching modules, it must be in the “R” (in) position. Front panel inputs...
Page 109 3-18 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Figure 3-6 Ω2 and Ω4 connections for front panel inputs Model 2750 Front Panel Optional Shield Shielded SENSE INPUT Ω 4 WIRE Cable 350V 1000V PEAK PEAK Resistance 500V PEAK...
Page 110: Standard Resistance Measurements
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-19 Figure 3-7 Ω2 and Ω4 connections for Model 7700 switching module Shielded Optional Shield Cable Model 7700 Resistance CH 1-20 Switching Under Test Module A. Ω2 Connections Model 7700 CH 11-20...
Page 111: Offset-Compensated Ohms
D-2, for details. It includes a flowchart showing where in the processing sequence that the OCOMP operation is performed. For a normal resistance measurement, the Model 2750 sources a current (I) and measures the voltage (V). The resistance (R) is then calculated (R=V/I) and the reading is displayed.
Page 112 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-21 The offset-compensated ohms reading is then calculated as follows: Offset-compensated ohms reading = ΔV/ΔI where: ΔV = V2 - V1 ΔI = I2 - I1 V1 is the voltage measurement with the current source at its normal level.
Page 113: Dry Circuit Ohms (Dryckt)
(such as temperature and humidity). Typically, the Ω4 function of the Model 2750 or a standard DMM is used to measure low resistance. However, if standard resistance measurements are performed, the relatively high open-circuit voltage may puncture the oxide film, and render the test meaningless.
Page 114 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-23 Measuring resistance of voltage-sensitive devices Dry circuit ohms should be used for any device that could be damaged by high open- circuit voltage. If not sure, and the slightly degraded accuracy is not a consideration, it is good practice to use dry circuit ohms to measure low resistance.
Page 115 DMM until 20mV is maintained at the DUT. The voltage is monitored at the Sense HI terminal. This allows the Model 2750 to accom- modate an additional 80% of range of path resistance per lead. So when measuring a 1Ω...
Page 116: Temperature Measurements
The equation to calculate thermocouple temperature is provided in Appendix When you connect a thermocouple directly to the input of the Model 2750, at least one of those connections will be a junction made up of two dissimilar metals. Hence, another voltage is introduced and is algebraically added to the thermocouple voltage.
Page 117 It is at the cold junction where dissimilar wire connections must be made. As long as the temperature of the cold junction is known, the Model 2750 can factor in the reference temperature to calculate the actual temperature reading at the thermocouple.
Page 118: Thermistors
DMM. If an intermittent open occurs in the thermocouple circuit, the capacitance could cause an erroneous on-scale reading. The Model 2750 has an open thermocouple detection circuit. When enabled, a 10µA pulse of current is applied to the thermocouple before the start of each temperature measure- ment.
Page 119: 4-Wire Rtds
The RTD has a metal construction (typically platinum). The resistance of the RTD changes with change in temperature. The Model 2750 measures the resistance and calcu- lates the temperature reading. When using default RTD parameters, the resistance of the RTD will be 100Ω...
Page 120 (assuming the user enters a precise reference temperature). With open thermocouple detection disabled, the Model 2750 can calculate the average temperature of two thermocouple channels using Channel Average (see Section 5 details).
Page 121 3-30 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Figure 3-8 Thermocouple connections Model 2750 Input HI Input LO Thermocouple Copper Wires Ice Bath Copper wire to thermocouple wire connection (one of two). A. Simulated Reference Junction (Front Panel Inputs)
Page 122 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-31 Table 3-3 Color codes — thermocouple wires T/C Type Positive (+) Negative (-) T/C Type Positive (+) Negative (-) U.S. White E U.S. Purple British Yellow Blue British Brown Blue...
Page 123 3-32 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Thermistor connections A thermistor can be connected directly to the front panel inputs or to any of the 20 input channels of the Model 7700 switching module as shown in Figure 3-9.
Page 124 Shown in Figure 3-10 are 4-wire RTD connections to the Model 2750. For the Model 7700 switching module, paired channels are used to perform the 4-wire measurement. The two input leads of the RTD are connected to a primary channel (1 through 10), while the two sense leads are connected to its paired channel (11 through 20).
Page 125: Temperature Measurement Configuration
3-34 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Temperature measurement configuration The Model 2750 is configured to measure temperature from the temperature measurement configuration menu. Use the following general rules to navigate through the menu structure: • Press SHIFT and then SENSOR to enter the menu structure.
Page 126 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-35 Thermistor temperature measurement configuration The steps to configure thermistor measurements are provided in Table 3-5. After pressing SHIFT and then SENSOR, the menu starts at step 1 to select measurement units.
Page 127: Temperature Measurement Procedure
3-36 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual The steps to configure 4-wire RTD measurements are provided in Table 3-7. After press- ing SHIFT and then SENSOR, the menu starts at step 1 to select measurement units. Each time you press ENTER to make a selection, the menu will automatically go to the next selection.
Page 128: Frequency And Period Measurements
Gate time The gate time is the amount of time the Model 2750 uses to sample frequency or period readings. Use the RATE key to set the gate time; SLOW sets the gate time to 1.0 sec, MED sets it to 0.1 sec, and FAST sets it to 0.01 sec.
Page 129: Connections
3-38 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Connections NOTE When using the front panel inputs, the INPUTS switch must be in the “F” (out) position. For switching modules, it must be in the “R” (in) position. Front panel input...
Page 130: Frequency And Period Measurement Procedure
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-39 Frequency and period measurement procedure NOTE Make sure the INPUTS switch is in the correct position. To use front panel inputs, it must be in the “F” (out) position. For switching modules, it must be in the “R”...
Page 131: Continuity Testing
Model 2750 Multimeter/Switch System User’s Manual Continuity testing The Model 2750 can test continuity using the 2-wire 1kΩ range. After selecting continuity, you will be prompted to enter the threshold resistance level (1 to 1000Ω). When the mea- sured circuit is below the set threshold level, the instrument will beep and display the resistance readings.
Page 132: Continuity Testing Procedure
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-41 Figure 3-13 Continuity connections Model 2750 Input HI Resistance Input LO Under Test A. Front Panel Connections Model 7700 Resistance CH 1-20 Switching Module Under Test B. Model 7700 Connections Note: Source current flows from input high to input low.
Page 133: Remote Programming For Basic Measurements
3-42 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Remote programming for basic measurements Basic measurement commands NOTE When measurements are performed, the readings are fed to other enabled pro- cessing operations. Appendix D explains “Data flow (remote operation)” and the commands used to return the various processed readings.
Page 134 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-43 Table 3-8 (continued) Basic measurement commands Commands Description Default Ref TEMP function [SENSe[1]] Optional root command. :TEMPerature:TRANsducer <name> Select temperature transducer; <name> = [, <clist>] TCouple, FRTD, or THERmistor. :TEMPerature:TCouple:TYPE <type>...
Page 135 3-44 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Table 3-8 (continued) Basic measurement commands Commands Description Default Ref PERIOD function :PERiod:THReshold:VOLTage:RANGe Select threshold voltage range; <n> = <n> [, <clist>] 0 to 1010. :PERiod:APERture <NRf> [, <clist>] Set gate time for PERIOD measurements in secs;...
Page 136 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-45 Reference FUNCtion <name> [, <clist>] Note that the <name> parameters in the table are enclosed in single quotes (‘ ’). However, double quotes (“ ”) can instead be used. For example: FUNC ‘VOLT:AC’...
Page 137 3-46 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual TEMPerature:FRTD:RZERo <NRf> [, <clist>] TEMPerature:FRTD:ALPHa <NRf> [, <clist>] TEMPerature:FRTD:BETA <NRf> [, <clist>] TEMPerature:FRTD:DELTa <NRf> [, <clist>] These commands are used to set the parameters for the USER RTD type. Note that the RZERo command sets the “Ω...
Page 138 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-47 DATA:FRESh? can only be used once to return the same reading string. That is, the reading must be “fresh.” Sending this command again to retrieve the same reading string will generate error -230 (data corrupt or stale), or cause a the GPIB to time-out.
Page 139: Basic Measurement Programming Examples
The following command sequence places the Model 2750 in a one-shot trigger mode to measure offset-compensated ohms. Whenever READ? is sent, a measurement will be trig- gered, and the measured reading will be sent to the computer when the Model 2750 is addressed to talk.
Page 140: Measurement Queries
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-49 Example #4 – Scan configuration (Model 7700) The following commands configure scan channels 101, 102, and 121 of a Model 7700 installed in slot 1. When channel 101 is scanned, DCV will be selected. When channel 102 is scanned, Ω2 will be selected.
Page 141: Read
3-50 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual :READ? What it does This command performs three actions. It will reset the trigger model to the idle layer (equivalent to the :ABORt command), take the trigger model out of idle (equivalent to the :INIT command), and return a reading (equivalent to a FETCh? query).
Page 142: [:Sense[1]]:Data:fresh
Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-51 [:SENSe[1]]:DATA:FRESh? What it does This query is similar to :FETCh? in that it returns the latest reading from the instrument but has the advantage of making sure that it does not return the same reading twice.
Page 143: Examples
3-52 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual Examples One-shot reading, DC volts, no trigger, fastest rate *RST :INITiate:CONTinuous OFF;:ABORt :SENSe:FUNCtion ‘VOLTage:DC’ // Use fixed range for fastest readings. :SENSe:VOLTage:DC:RANGe 10 // Use lowest NPLC setting for fastest :SENSe:VOLTage:DC:NPLC 0.01...
Page 144 Model 2750 Multimeter/Switch System User’s Manual Basic DMM Operation 3-53...
Page 145 3-54 Basic DMM Operation Model 2750 Multimeter/Switch System User’s Manual...
Page 146: Range, Digits, Rate, Bandwidth, And Filter Range
Range, Digits, Rate, Bandwidth, and Filter • Range — Provides details on measurement range selection. Includes the com- mands for remote programming. • Digits — Provides details on selecting display resolution. Includes the commands for remote programming. • Rate and bandwidth — Provides details on integration rate and bandwidth (for AC measurements).
Page 147: Measurement Ranges And Maximum Readings
Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Range The range setting is “remembered” by each measurement function. When you select a function, the instrument will return to the last range setting for that function. Measurement ranges and maximum readings The selected range affects both accuracy of the measurement as well as the maximum level that can be measured.
Page 148: Auto Ranging
Auto ranging should not be used when optimum speed is required. Note that the AUTO key has no effect on temperature (TEMP). Up-ranging occurs at 120% of range. The Model 2750 will down-range when the reading is <10% of nominal range.
Page 149: Remote Programming - Range
Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Remote programming — range Range commands The commands to set range are listed in Table 4-2. Additional information on these com- mands follow the table. NOTE Query commands and some optional command words are not included in Table 4-2.
Page 150: Digits
' Set 101 for 10V range. Digits The DIGITS key sets display resolution for the Model 2750 from 3H to 6H digits. From the front panel, setting digits for one function affects all the other functions. For example if you set DCV for 3H digits, the other functions will also set to 3H digits. For remote pro- gramming, each mainframe input function can have its own unique digits setting.
Page 151: Remote Programming - Digits
Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Remote programming — digits Digits commands The commands to control display resolution (digits) are listed in Table 4-3. Additional information on these commands follow the table. NOTE Query commands are not included in Table 4-3.
Page 152 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter Setting digits Even though the parameters for the DIGits command are expressed as integers (4 to 7), you can specify resolution using a real number. For example, to select 3H digit resolution, let <n>...
Page 153: Rate And Bandwidth
4-1. The Model 2750 is optimized for the 1 PLC to 5 PLC reading rate. At these rates (lowest noise region in graph), the Model 2750 will make corrections for its own internal drift and still be fast enough to settle a step response <100ms.
Page 154 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter The front panel RATE settings for all but the AC functions are explained as follow: • FAST sets integration time to 0.1 PLC. Use FAST if speed is of primary impor- tance (at the expense of increased reading noise and fewer usable digits).
Page 155: Bandwidth
SLOW) turns on. NOTE The Model 2750 uses internal references to calculate an accurate and stable reading. When the NPLC setting is changed, each reference must be updated to the new NPLC setting before a reading is generated. Therefore, frequent NPLC setting changes can result in slower measurement speed.
Page 156: Remote Programming - Rate And Bandwidth
Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-11 Remote programming — rate and bandwidth Rate and bandwidth commands The commands to set the integration rate and bandwidth are listed in Table 4-5. Additional information on these commands follows the table.
Page 157 4-12 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Table 4-5 (continued) Rate and bandwidth commands 1, 7 Commands Description Default Bandwidth commands [SENSe[1]] Optional root command. :VOLTage:AC:DETector:BANDwidth Set AC bandwidth for ACV in Hertz; <NRf> = <NRf>...
Page 158 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-13 To set bandwidth, simply specify (approximately) the frequency of the input signal. The instrument will automatically set the bandwidth as follows: <NRf> = 3 to 29 3Hz to 300kHz...
Page 159: Filter
4-14 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Filter The digital filter is used to stabilize noisy measurements. The displayed, stored, or trans- mitted reading is a windowed-average of a number of reading conversions (from 1 to 100).
Page 160 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-15 For voltage, current, and resistance, the filter window is expressed as a percent of range. For example, on the 10V range, a 10% window means that the filter window is ±1V. For temperature, the filter window is expressed as a percent of the maximum temperature reading.
Page 161 4-16 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Figure 4-2 Moving and repeating filters Conversion Conversion Conversion Average Average Average Reading Reading Reading Conversion Conversion Conversion A. Type - Moving Average, Readings = 10 Conversion...
Page 162 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-17 NOTE Bit 8 of the Operation Event Status Register sets when the filter window has properly settled (or the filter is disabled). See Section “Status Structure,” for details.
Page 163 4-18 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Figure 4-3 Filter configuration flow chart SHIFT TYPE 0.01% 0.1% WINDOW NONE 001 to 100 RDGS REPEAT TYPE MOVNG AV Scanning The moving filter cannot be used when scanning. A scan channel cannot be configured to use the moving filter.
Page 164: Remote Programming - Filter
Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-19 Remote programming — filter Filter commands The filter commands are listed in Table 4-6. Additional information on these commands follow the table. NOTE Query commands are not included in Table 4-6.
Page 165 4-20 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Table 4-6 (continued) Filter commands 1, 4 Commands Description Default DCI filter commands [SENSe[1]] Optional root command. :CURRent[:DC]:AVERage:TCONtrol <name> Select filter type; <name> = MOVing or (Note 2) REPeat.
Page 166 Model 2750 Multimeter/Switch System User’s Manual Range, Digits, Rate, Bandwidth, and Filter 4-21 Table 4-6 (continued) Filter commands 1, 4 Commands Description Default Ω4 filter commands [SENSe[1]] Optional root command. :FRESistance:AVERage:TCONtrol <name> Select filter type; <name> = MOVing or (Note 2) REPeat.
Page 167 4-22 Range, Digits, Rate, Bandwidth, and Filter Model 2750 Multimeter/Switch System User’s Manual Filter programming examples Example #1 — The following command sequence configures filtering for the DCI function: CURR:TCON MOV ' Select the moving filter. CURR:AVER:WIND 0.01 ' Set filter window to 0.01%.
Page 168: Relative, Math, Ratio, Channel Average, And Db
Relative, Math, Ratio, Channel Average, and dB • Relative — Explains how to null an offset or establish a baseline value. Includes the commands for remote programming. • Math — Covers the three basic math operations: mX+b, percent, and reciprocal (1/X).
Page 169: Relative
Selecting a range that cannot accommodate the rel value does not cause an overflow con- dition, but it also does not increase the maximum allowable input for that range. For exam- ple, on the 10V range, the Model 2750 still overflows for a 12V input. NOTE The various instrument operations, including Relative, are performed on the input signal in a sequential manner.
Page 170 Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB Pressing REL a second time disables rel. You can input a rel value manually using the mX+b function. Set M for 1 and B for any value you want. The mX+b function is covered in this section (see “Math,”...
Page 171: Remote Programming - Rel
Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Remote programming — rel Rel commands The rel commands to set range are listed in Table 5-1. Additional information on these commands follow the table. NOTE Query commands are not included in Table 5-1.
Page 172 Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB Table 5-1 (continued) Rel commands Commands Description Default Rel commands for ACI [SENSe[1]] Optional root command. :CURRent:AC:REFerence <n> [, <clist>] Specify rel value; <n> = -3.1 to 3.1 (A).
Page 173 Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Table 5-1 (continued) Rel commands Commands Description Default Rel commands for PERIOD [SENSe[1]] Optional root command. :PERiod:REFerence <n> [, <clist>] Specify rel value; <n> = 0 to 1 (sec).
Page 174 Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB value. When rel is set using :ACQuire, the :REFerence? query command returns the acquired rel value. Rel programming examples Example #1 — The following command sequence zeroes the display for DCV.
Page 175: Math
Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Math The Model 2750 has three built-in math calculations that are accessed from the MATH menu: mX+b, percent, and reciprocal (1/X). Figure 5-1 shows the MATH menu tree. Note that the settings shown in the menu tree are the factory defaults.
Page 176: Mx+B
Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB mX+b This math operation lets you manipulate normal display readings (X) mathematically according to the following calculation. Y = mX + b where: X is the normal display reading.
Page 177: Percent
5-10 Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual mX+b rel The mX+b function can be used to manually establish a rel value. To do this, set the scale factor (M) to 1 and set the offset (b) to the rel value. Each subsequent reading will be the difference between the actual input and the rel value (offset).
Page 178: Reciprocal (1/X)
Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB 5-11 Reciprocal (1/X) The reciprocal of a reading is displayed when the reciprocal (1/X) math function is enabled: Reciprocal = 1/X where: X is the normal input reading The displayed units designator for reciprocal readings is “R.”...
Page 179: Basic Operation
5-12 Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Basic operation NOTE If using switching module inputs, make sure the front panel INPUTS switch is set to the REAR position (in). If using the front panel inputs, the switch must be in the FRONT position (out).
Page 180: Remote Programming - Math
Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB 5-13 Remote programming — math Math commands NOTE When measurements are performed, the readings are fed to other enabled pro- cessing operations, including Math. Appendix D explains “Data flow (remote operation)”...
Page 181 5-14 Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Setting mX+b units The <char> parameter for CALCulate:KMATh:MUNits must be one character enclosed in single or double quotes. It can be any letter of the alphabet, the degrees symbol (°) or the ohms symbol (Ω).
Page 182 Example #1 — The following command sequence performs the mX+b calculation for channels 101 and 102 of the Model 7700. Keep in mind that after CALC:DATA? is sent, the Model 2750 has to be addressed to talk to send the math result to the computer. CALC:FORM MXB ' Select mX+b calculation.
Page 183: Ratio And Channel Average
Model 2750 Multimeter/Switch System User’s Manual Ratio and channel average With a switching module installed in the Model 2750, the ratio or average of two channels can be calculated and displayed. The ratio calculation can be done on the DCV function, and the channel average calculation can be done on the DCV and TEMP (thermocouples only) functions.
Page 184: Basic Operation
Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB 5-17 Basic operation NOTE Make sure the INPUTS switch is set to the REAR position (in). Select and configure (range, filter, rel, etc.) a valid measurement function. For ratio, the only valid function is DCV.
Page 185 5-18 Rel, Math, Ratio, Channel Average, dB Model 2750 Multimeter/Switch System User’s Manual Scanning Ratio and channel average can be used in an advanced scan. The 2-channel scan for the calculation is performed for every primary channel that is scanned. For example, assume the Model 7700 is installed in slot 1 and is configured to perform the ratio calculation for 10 channels.
Page 186: Remote Programming - Ratio And Channel Average
Model 2750 Multimeter/Switch System User’s Manual Rel, Math, Ratio, Channel Average, dB 5-19 Remote programming — ratio and channel average Ratio and channel average commands The ratio and channel average are listed in Table 5-3. Details on these commands follow the table.
Page 187 Ratio and channel average programming examples Example #1 — The following command sequence performs the ratio calculation using primary channel 102 of the Model 7700. After READ? is sent, the Model 2750 must be addressed to talk to return the result of the calculation.
Page 188: Remote Programming - Db
= 1µV and V = 1000V. dB configuration Remote programming must be used to configure the Model 2750 for dB measurements. It cannot be configured from the front panel. Scanning Typically a scan using dB is configured and run using remote programming. However, once dB is selected using remote programming, a simple dB scan can be configured and run from the front panel.
Page 189 101 is set for the ACV function. Programming examples — dB Example #1 — The following command sequence configures the Model 2750 to perform DCV dB measurements. A 1V input will be measured as 0dB.
Page 190: Buffer
Buffer • Buffer overview — Summarizes basic buffer (data store) capabilities. • Front panel buffer — Explains how to store and recall readings, and discusses the various statistics available on buffer data including minimum and maximum val- ues, average (mean), standard deviation, and peak-to-peak values. •...
Page 191: Buffer Overview
Model 2750 Multimeter/Switch System User’s Manual Buffer overview The Model 2750 has a data store (buffer) to store from 2 to 110,000 readings. The instru- ment stores the readings that are displayed during the storage process. Each timestamped reading includes the buffer location number and a timestamp.
Page 192: Timestamps
Buffer NOTE If the buffer is empty when the Model 2750 is turned off, buffer auto clear will enable when it is turned back on. If the buffer is not empty, the instrument will power up to the last auto clear set- ting.
Page 193 Therefore, the timestamp for the 11th reading (#10) is one hour (3600 seconds). When the Model 2750 is turned off, the relative timestamp resets to 0sec when the instrument is turned back on. If you have readings stored in the buffer and auto clear is disabled when the unit is turned off, subsequent stored readings will be appended to the old group of readings.
Page 194: Storing Readings
Use the key to display the relative (REL) or real-time clock (RTCL), and press ENTER. Storing readings Perform the following steps to store readings: Set up the Model 2750 for the desired configuration. Press the STORE key. Δ ∇ Use the...
Page 195: Recalling Readings
Buffer Model 2750 Multimeter/Switch System User’s Manual Recalling readings Readings stored in the buffer are displayed by pressing the RECALL key. The readings are positioned at the left side of the display, while the buffer location number (reading num- ber) and timestamps are positioned at the right side.
Page 196 Model 2750 Multimeter/Switch System User’s Manual Buffer Figure 6-2 Recalling buffer data — real-time clock timestamp Reading Value Time Date Reading Value Time Date Reading Value Time Date Reading Value Time Date Reading Value Time Date Reading Value Time Date...
Page 197: Remote Programming - Buffer
If the standard deviation calculation is being performed on a buffer that has more than 1000 readings, the “CALCULATING” message will flash to indicate that the Model 2750 is busy. While busy with the calculation, front panel keys will not operate.
Page 198 Model 2750 Multimeter/Switch System User’s Manual Buffer NOTE Optional command words and most queries are not included in Table 6-1. The unabridged tables for all SCPI commands are provided in Section Table 6-1 Buffer commands Command Description Default SYSTem:TIME <hr, min, sec>...
Page 199 6-10 Buffer Model 2750 Multimeter/Switch System User’s Manual SYSTem:TIME <hr, min, sec> Set clock time Use to set the clock time in the 24-hour format (hr/min/sec). Seconds can be set to 0.01 sec resolution. Examples: SYST:TIME 13, 23, 36 ' Set time to 1:23:36 PM.
Page 200 Model 2750 Multimeter/Switch System User’s Manual Buffer 6-11 TRACe:POINts 2 to 110000 Set buffer size With buffer auto-clear enabled, you can set the buffer to store from 2 to 110,000 readings. A buffer size of zero or one is not valid (error -222).
Page 201 6-12 Buffer Model 2750 Multimeter/Switch System User’s Manual TRACe:DATA:SELected? <start>, <count> Specify readings to return TRACe:NEXT? Query location of last buffer reading Use the TRACe:DATA:SELected? command to specify which stored readings to return. The <start> parameter specifies the first stored reading to return. Note that the first stored read- ing in the buffer is #0.
Page 202 Model 2750 Multimeter/Switch System User’s Manual Buffer 6-13 FORMat:ELEMents <item list> Select elements for TRACe:DATA? <item list> = READing, CHANnel, UNITs, RNUMber, TSTamp The data returned by TRACe:DATA? can include from one to all five data elements shown in the above item list. For example, if you want the units and reading number included with the reading, you would send this command: FORMat:ELEMents READing, UNITs, RNUMber.
Page 203: Programming Example
*OPC and *OPC? Programming example The following command sequence stores 20 readings in the buffer and then calculates the mean for those readings. Note that after sending a query command, the Model 2750 must be addressed to talk. ' Store readings: TRAC:CLE:AUTO ON ' Enable buffer auto-clear.
Page 204 Model 2750 Multimeter/Switch System User’s Manual Buffer 6-15...
Page 205 6-16 Buffer Model 2750 Multimeter/Switch System User’s Manual...
Page 206: Scanning
Scanning • Scanning fundamentals — Explains channel assignments (slot/channel program- ming format), the difference between sequential and non-sequential scans, and the basic scan process. Block diagrams (known as trigger models) are provided to help explain the STEP and SCAN operations. •...
Page 207: Scanning Fundamentals
Model 2750 Multimeter/Switch System User’s Manual Scanning fundamentals The Model 2750 can scan the channels of up to five installed Keithley switching modules. Each scan channel can have its own unique setup. Aspects of operation that can be uniquely set for each channel include function, range, rate, AC bandwidth, rel, filter, dig- its, math, Ω...
Page 208: Channel Assignments
Model 2750 Multimeter/Switch System User’s Manual Scanning Channel assignments A switching module has a certain number of channels. For example, the Model 7700 switching module has 22 channels (1 through 22). When you encounter a 1 or 2-digit channel number in this manual, the switching module channel is the point of discussion.
Page 209: Trigger Models
Scanning Model 2750 Multimeter/Switch System User’s Manual closed channels, (2) close the paired channels, and then (3) perform the 4-wire measure- ment. The last scanned channel pair opens. NOTE For the Model 7700 switching module, primary channels 1 through 10 are paired to channels 11 through 20.
Page 210 Model 2750 Multimeter/Switch System User’s Manual Scanning Figure 7-1 Trigger model with STEP function Enable Scan Close First Chan in List Another Trigger Reading Counter (Reading Count) Event Control Detection Source Open Last Chan Immediate Close Next Chan External in List...
Page 211 Scanning Model 2750 Multimeter/Switch System User’s Manual Figure 7-2 Trigger model with SCAN function Enable Scan Close First Chan in List Trigger Another Counter Scan? Event Control Detection Source Immediate External Timer Timer Manual* Output Enabled Bus* Trigger Timer Bypass Timer >...
Page 212 After the last channel in the scan list is measured, the Model 2750 outputs a trigger pulse. If programmed to again scan the channels in the scan list, the Model 2750 will wait at the control source for another trigger event. After all the scan list channels are again mea- sured, the Model 2750 will output another trigger pulse.
Page 213 Scanning Model 2750 Multimeter/Switch System User’s Manual Immediate control source With immediate triggering, event detection is immediate allowing channels to be scanned. Timer control source With the timer source enabled (selected), event detection is immediately satisfied. On the initial pass through the loop, the Timer Bypass is enabled allowing operation to bypass the Timer and continue to the Delay block.
Page 214 Model 2750 Multimeter/Switch System User’s Manual Scanning Delay (Auto or Manual) — The user can select either auto delay or manual delay. With auto delay selected, the instrument automatically selects a delay period that will provide sufficient settling for function and autorange changes, and multi-phase measurements.
Page 215 7-10 Scanning Model 2750 Multimeter/Switch System User’s Manual SCAN operation — When a scan is started, one or more complete scans will be per- formed. The number of channels in the scan list determines the number of channels for each scan. The reading count determines the number of scans to perform and is best explained by an example.
Page 216: Scan Configuration
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-11 Scan configuration A scan is configured from the scan configuration menu which is accessed by pressing SHIFT and then CONFIG. Figure 7-3 shows the basic flowchart to configure a scan. After entering the menu structure you can configure a simple scan, an advanced scan, or reset the configuration to the default setup for a simple scan.
Page 217 7-12 Scanning Model 2750 Multimeter/Switch System User’s Manual There are two scan configurations: simple and advanced. When you configure the simple scan, the instrument uses the present instrument setup for each channel in the scan. For the advanced scan, each channel can have its own unique setup. As explained in “Trigger...
Page 218: Scan Reset
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-13 Scan reset From the scan configuration menu, you can reset the scan configuration to the default setup for a simple scan. For the Model 7700 switching module, channels 21 and 22 are turned off (not used), and...
Page 219: Advanced Scan
7-14 Scanning Model 2750 Multimeter/Switch System User’s Manual If you enabled the timer, set the timer interval using the hour/minute/second for- mat. The timer can be set from 0.001 sec (00H:00M:00.001S) to 99 hrs, 99 min, 99.999 sec (99H:99M:99.999S). Note that pressing the AUTO key sets the timer to 0.001 sec.
Page 220 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-15 Advanced scan setup notes The CHAN annunciator is on while in the scan setup menu. For some channel-specific setups, you have to configure them from a menu. For example, to set up and enable mX+B, you have to use MATH menu. While in that menu, the CHAN annunciator will flash to indicate that you are editing the mX+b math setup for that channel in the scan list.
Page 221 7-16 Scanning Model 2750 Multimeter/Switch System User’s Manual Advanced scan setup procedure Step 1: Select the advanced scan configuration menu Press SHIFT and then CONFIG to access the scan setup menu. Δ ∇ Press the key to display INT: ADVANCED and press ENTER.
Page 222: Setting Delay
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-17 Step 3: Enable immediate scan The present state of immediate scan (IMM SCAN) is displayed; Y (yes, which is the fac- tory and *RST default) or N (no). With immediate scan enabled, the scan will start when Δ...
Page 223: Monitor Channel
7-35. NOTE An overflow reading (“OVRFLW” message displayed) is interpreted by the Model 2750 as a positive reading, even if the input signal is negative. This could inadvertently trigger a monitor scan (see “(see Scan operation) — Monitor scan,”...
Page 224: Auto Channel Configuration
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-19 Method 1: Use the CLOSE key or the keys to close the channel that you want to be the monitor. Press SHIFT and then MONITOR (MON annunciator turns on). Method 2: If a channel is closed, press OPEN to open it.
Page 225: Saving Setup
When auto scan is enabled, the scan operation is saved in memory. If power to the Model 2750 is interrupted, the scan will resume when power is restored. With auto scan enabled, the last scan setup becomes the power-on setup. It takes precedence over the fac- tory, *RST or user-saved power-on setup.
Page 226: Scan Operation
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-21 resumed. Error +517 occurs (cannot resume scan) to indicate that the scan has been disabled. The instrument assumes the normal power-on setup. The Model 7706 does not support auto scan. Trying to enable auto scan with a Model 7706 card installed will cause error -221 (settings conflict).
Page 227 7-22 Scanning Model 2750 Multimeter/Switch System User’s Manual NOTE Channels for an advanced scan can be configured using different mX+B units (i.e., ° and ¾), temperature sensors (I.e., 4-wire RTD and thermistor), and mea- surement type (i.e., OCOMP ohms and DCV).
Page 228: Manual/External Trigger Scan
After the last scan is completed, the scan remains enabled (SCAN annunciator on), but the Model 2750 goes into the idle state. If you wish to repeat the scans, you will have to first take the Model 2750 out of idle. This can be done by pressing the SCAN (or TRIG) key.
Page 229: Monitor Scan (Analog Trigger)
NOTE An overflow reading (“OVRFLW” message displayed) is interpreted by the Model 2750 as a positive reading, even if the input signal is negative. This could inadvertently trigger a monitor scan. For example, assume the monitor channel is monitoring a negative input signal, and the instrument is configured to trigger a monitor scan if a positive input signal is detected.
Page 230 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-25 Δ ∇ Press the key to enable or disable low limit 1 (LLIM1 SCAN:N/Y), and press ENTER. Δ ∇ Press the key to enable or disable high limit 1 (HLIM1 SCAN:N/Y), and press ENTER.
Page 231: Remote Programming - Scanning
7-26 Scanning Model 2750 Multimeter/Switch System User’s Manual Remote programming — scanning NOTE Scanning examples (remote programming and front panel operation) are pro- vided at the end of this section. Trigger model The trigger model for bus operation is shown in Figure 7-2.
Page 232: Channel Setup
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-27 Channel setup The <clist> parameter is used to set up scan channels. For example, the following exam- ples show how to set up scan channel 101: FUNC 'VOLT', (@101) ' Set 101 for DCV.
Page 233 7-28 Scanning Model 2750 Multimeter/Switch System User’s Manual Table 7-1 Scanning commands Commands Description Default Ref Scan commands ROUTe:SCAN <clist> Specify list of channels to be scanned. ROUTe:SCAN? Returns list of channels to be scanned. ROUTe:SCAN:TSOurce <list> Select trigger(s) to start scan; <list> = IMMediate, or HLIMit1, LLIMit1, HLIMit2, LLIMit2.
Page 234 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-29 Table 7-1 (continued) Scanning commands Commands Description Default Ref Trigger commands TRIGger:SOURce <name> Select control source; <name> = IMMediate, TIMer, MANual, BUS, or EXTernal. TRIGger:TIMer <n> Set timer interval in sec; <n> = 0.001 to 999999.999.
Page 235 7-30 Scanning Model 2750 Multimeter/Switch System User’s Manual Reference ROUTe:SCAN <clist> — Channels will be scanned in the order that they are listed. The following example shows the proper format for specifying channels in a scan list for a sequential scan:...
Page 236 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-31 For the 4-wire resistance function, channels 101through 110 will be paired to chan- nels 111 through 120. ROUT:SCAN? returns the following scan list: (@101:110) Now assume the scan is returned to DCV function as follows: SENS:FUNC ‘VOLT’,(@101:120)
Page 237: Scanning Programming Example
7-32 Scanning Model 2750 Multimeter/Switch System User’s Manual SAMPle:COUNt and TRIGger:COUNt — Sample count specifies the number of readings to scan and store in the buffer, while the trigger count specifies the num- ber of scans to perform. If the sample count is greater than the number of channels in the scan list (scan list length), operation wraps around to the beginning of the scan list and continues.
Page 238: Scanning Examples
Model 2750 Multimeter/Switch System User’s Manual Scanning 7-33 Scanning examples The following scanning examples assume that the Model 7700 switching module is installed in slot 1 of the mainframe. Tables are used for the procedure steps to configure and run scan examples. The left side of the table provides the front panel procedure, while the right side shows the equivalent remote programming commands.
Page 239 As shown in the operation model, when the scan is enabled, channel 101 closes and the Model 2750 waits for an external trigger. When the trigger is received, channels 101 and 102 are measured. Operation then returns to the control source where it waits for another trigger.
Page 240 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-35 Table 7-2 External trigger scan example Front panel operation Remote programming Restore defaults: Restore defaults (SHIFT SETUP > RESTORE: FACT). *RST For front panel operation, proceed to step 3. For remote programming, clear buffer and disable...
Page 241: Monitor Scan
30°C, the instrument will remain in the moni- tor mode. When the temperature reading reaches 30°C, the Model 2750 switches over to the scan mode. Figuratively speaking, it is as if a “finger” presses the SCAN key when the monitor detects that the average temperature is at or above 30°C.
Page 242 Model 2750 Multimeter/Switch System User’s Manual Scanning 7-37 Figure 7-5 Monitor scan example Monitor Mode: Close Monitor Channel (101) ≥30˚C SCAN Measure TEMP Scan Mode: Close First Return to Channel Monitor Mode Measurements Open Last Chan Close Next Chan Measure...
Page 243 7-38 Scanning Model 2750 Multimeter/Switch System User’s Manual Table 7-3 Monitor scan example Front panel operation Remote programming Restore defaults (SHIFT SETUP > RESTORE: FACT). SYST:PRES For front panel operation, proceed to step 3. For remote programming, clear the buffer:...
Page 244: Triggering
Trigger model — Explains the various components of the front panel trigger model, which controls the triggering operations of the instrument. • External triggering — Explains external triggering which allows the Model 2750 to trigger and be triggered by other instruments. •...
Page 245: Trigger Model
Triggering Model 2750 Multimeter/Switch System User’s Manual Trigger model The flow chart in Figure 8-1 summarizes triggering as viewed from the front panel. It is called a trigger model because it is modeled after the SCPI commands used to control triggering.
Page 246: Control Source And Event Detection
An input trigger via the Trigger Link line EXT TRIG is received. • The front panel TRIG key is pressed. (The Model 2750 must be taken out of remote before it will respond to the TRIG key. Use the LOCAL key or send GTL over the bus.)
Page 247 Triggering Model 2750 Multimeter/Switch System User’s Manual Table 8-1 Auto delay settings Function Range and delay 100mV 100V 1000V 100mV 100V 750V 400ms 400ms 400ms 400ms 400ms FREQ and 100mV 100V 750V PERIOD 20mA 100mA 400ms 400ms Ω2, Ω4 1Ω...
Page 248: Device Action
Channel Closure. Channel Closure — When scanning, the last device action is channel control. The • Model 2750 opens the presently closed channel, and then closes the next channel in the scan. Output trigger After the device action, an output trigger occurs and is available at the rear panel Trigger Link connector.
Page 249: External Triggering
Digital I/O Pin 6 (Ext Trig) of the Digital I/O can also be used as the external trigger input for the Model 2750. Line 2 of the TRIG LINK is physically connected to pin 6 of the Digital I/O connector.
Page 250: External Trigger
The VMC output provides a TTL-compatible output pulse that can be used to trigger other instruments. The specifications for this trigger pulse are shown in Figure 8-5. Typically, you would want the Model 2750 to output a trigger after the settling time of each measurement. Figure 8-5 Trigger link output pulse specifications (VMC)
Page 251: External Triggering Example
Model 2750 Multimeter/Switch System User’s Manual External triggering example For a test system that requires a large number of switching channels, the Model 2750 can be used with external scanners such as the Keithley Models 7001 and 7002. For example,...
Page 252 8-7. Trigger Link of the Model 2750 is connected to Trigger Link (either IN or OUT) of the Model 7002. Note that with the default trigger settings on the Model 7002, line #1 is an input and line #2 is an output.
Page 253 Scanned Channels Pressing EX TRIG on the Model 2750 places it at point A in the flowchart, where it is waiting for an external trigger. Pressing STEP on the Model 7002 takes it out of the idle state and places operation...
Page 254: External Triggering With Bnc Connections
(point F) and then loops back to point A where it waits for another input trigger. The trigger applied to the Model 7002 from the Model 2750 closes the next channel in the scan. This triggers the Model 2750 to measure the next DUT. The process continues until all 400 channels are scanned, measured, and stored in the buffer.
Page 255: Remote Programming - Triggering
SLOT COVER Model 2750 Remote programming — triggering Trigger model (remote operation) The following paragraphs describe how the Model 2750 operates for remote operation. The flow chart in Figure 8-10 summarizes operation over the bus. The flow chart is called the trigger model because operation is controlled by SCPI commands from the Trigger subsystem.
Page 256 Model 2750 Multimeter/Switch System User’s Manual Triggering 8-13 What happens next depends on the state of initiation. If continuous initiation is already enabled, the instrument will leave the idle state. SYSTem:PRESet enables continuous ini- tiation. Therefore, operation will immediately leave the idle state when it is sent. The *RCL command will do the same if INITiation:CONTinuous ON is a user saved default.
Page 257 8-14 Triggering Model 2750 Multimeter/Switch System User’s Manual Figure 8-10 Trigger model (remote operation) :ABOrt *RCL 0 START :SYST:PRES *RST :INIT (:IMM) Idle :INIT:CONT ON Initiate :INIT (:IMM) :INIT:CONT ON :Trigger:Signal Another Trigger Event Control Detection Source :Trigger:Count<n> | INFinity...
Page 258: Trigger Model Operation
= 2), those five new readings will overwrite the original five readings in the buffer. Output Trigger — The Model 2750 will send one or more output triggers. The output trigger is applied to the Trigger Link connector on the rear panel. It can be used to trigger...
Page 259: Triggering Commands
Loop around control source. SAMPle :COUNt <NRf> Set sample count; 1 to 110000. *RST Restore *RST defaults (see “Default” column of this table). Places 2750 in the idle state. Notes: 1. Defaults for continuous initiation: SYSTem:PRESet enables continuous initiation. *RST disables continuous initiation.
Page 260: Programming Example
Programming example The following program fragment triggers (and stores in the buffer) 10 readings. Note that in order to send the readings to the computer, you must address the Model 2750 to talk after sending READ?. *RST ' Restore *RST defaults.
Page 261 8-18 Triggering Model 2750 Multimeter/Switch System User’s Manual...
Page 262: Limits And Digital I/O
Limits and Digital I/O • Limits — Explains how to perform limit tests on measured readings. • Digital I/O — Covers the digital I/O port. Explains how the five digital outputs respond to the results of limit tests. • Remote programming — limits and digital output — Summarizes the com- mands to perform limit tests and control the digital I/O port.
Page 263: Limits
Limits and Digital I/O Model 2750 Multimeter/Switch System User’s Manual Limits NOTE Limits cannot be used with the CONT function. When using limits, you can set and control the values that determine the HIGH/IN/LOW status of subsequent measurements. The limit test is performed on the result of an enabled Rel, Math, Ratio, or Channel Average operation.
Page 264 The LOW annunciator is not used for an overflow reading. An overflow reading is inter- preted by the Model 2750 as a positive reading, even if the input signal is negative. That is the reason why the LOW annunciator does not turn on.
Page 265: Scanning
Limits and Digital I/O Model 2750 Multimeter/Switch System User’s Manual Scanning When a simple scan is configured, the present limit values and state will apply to all chan- nels in the scan. When an advanced scan is configured, each channel can have its own unique limits configuration.
Page 266: Digital I/O
Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O Digital I/O Model 2750’s Digital I/O port is accessed at a male DB-9 connector located on the rear panel. The connector location and pin designations are shown in Figure 9-2.
Page 267: Digital Outputs
Limits and Digital I/O Model 2750 Multimeter/Switch System User’s Manual Digital outputs The digital I/O port has five digital outputs. Each digital output can be used as a sink to control devices (e.g., relays), or as a source to provide input to external logic (TTL or CMOS) circuitry.
Page 268 Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O Logic sense The selected logic sense (active high or active low) determines if an output is pulled high or low when the limit is reached. If logic sense is set high, the output line will be pulled high when the reading reaches or exceeds the limit.
Page 269 Limits and Digital I/O Model 2750 Multimeter/Switch System User’s Manual Sink mode — controlling external devices Each output can be operated from an external supply (voltage range from +5V to +33V applied through the external device being driven). The high current sink capacity of the output driver allows direct control of relays, solenoids, and lamps (no additional circuitry needed).
Page 270 Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O Figure 9-4 Controlling externally powered relays Model 2750 Pin 7 - Diode Clamp Relay Coil Digital Output #1 4.75kΩ Flyback Diode External Power Pull Up Resistor (+5V to +33V) Digital Output...
Page 271 CAUTION Each output line can source up to 200µA. Exceeding 200µA may cause damage to Model 2750 that is not covered by the warranty. Figure 9-5 shows how to connect a logic device to one of the output lines. When the out- put line is pulled high, the transistor will turn off (transistor switch open) to provide a reli- able logic high output (>3.75V).
Page 272: Setting Digital Output
Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O 9-11 Setting digital output The OUTPUT menu (shown in Table 9-1) is used to control and configure digital outputs. Menu items for the digital output include: • DOUTPUT — Use to enable (ON) or disable (OFF) the digital outputs.
Page 273: Scanning
While limits can be configured on a per scan channel basis, the digital output configura- tion cannot. Therefore, for all scan channels that are set to use limits, the digital output will function according to how the Model 2750 is set up when the scan is run.
Page 274: Remote Programing - Limits And Digital Output
Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O 9-13 Remote programing — limits and digital output Limits and digital output commands The limits and digital output commands are provided in Table 9-2. Table 9-2 Limits and digital I/O commands...
Page 275 9-14 Limits and Digital I/O Model 2750 Multimeter/Switch System User’s Manual Table 9-2 (continued) Limits and digital I/O commands Commands Description Digital output commands CALCulate3:OUTPut:LSENse <name> Set logic sense; <name> = AHIGh or ALOW. AHIGh CALCulate3:OUTPut:[STATe] <b> Enable/disable digital outputs; <b> = ON or OFF.
Page 276: Limits And Digital Outputs Programming Example
:CLEar command. Limits and digital outputs programming example The following command sequence configures the Model 2750 to perform Limit 1 test on a DCV reading. If the 100mV limit is reached, digital output # 2 will be pulled low. If the -100mV limit is reached, digital output #1 will be pulled low.
Page 277: Application - Sorting Resistors
5%. Bin 3 is for resistors that exceed 5% tolerance. The digital outputs of the Model 2750 can be used to further automate the test system by controlling a compatible component handler to perform the binning operations.
Page 278 Model 2750 Multimeter/Switch System User’s Manual Limits and Digital I/O 9-17 Limit 1 will be used to test for the 1% tolerance and Limit 2 will be used to test for the 5% tolerance. The resistance values for the 1% and 5% tolerances are calculated as follows: = 100Ω...
Page 279: Digital Outputs
Keep in mind that a fail condition must be reset before testing the next resistor. Fail can be reset manually or automatically (see Table 9-2, CLEar command). Digital outputs With the digital outputs of the Model 2750 enabled, the digital outputs will respond as fol- lows for each resistor reading: Resistor Affected LO limit 2...
Page 280: Remote Operations
Front panel GPIB operation — Summarizes GPIB error messages, status indica- tors, and using the LOCAL key. • Programming syntax — Describes the basic programming syntax for both com- mon and SCPI commands. • RS-232 interface operation — Outlines use of the RS-232 interface to control the Model 2750.
Page 281: Operation Enhancements
A pseudocard cannot be installed from the front panel. However, once it is installed, you can take the Model 2750 out of remote and use the front panel. When the instrument is turned off, the pseudocard will be lost (uninstalled).
Page 282: Separate Function Setups
Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-3 Separate function setups A few settings from the front panel are global. That is, the setting on one function also applies to the other functions. For example, if you set DCV for 3H digits, all the other func- tions will also be set to 3H digits.
Page 283: Gpib Setup
The above standards define a syntax for sending data to and from instruments, how an instrument interprets this data, what registers should exist to record the state of the instru- ment, and a group of common commands. The Model 2750 also conforms to this standard: •...
Page 284: Gpib Connections
Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-5 GPIB connections To connect the Model 2750 to the GPIB bus, use a cable equipped with standard IEEE-488 connectors as shown in Figure 10-1. Figure 10-1 IEEE-488 connector To allow many parallel connections to one instrument, stack the connectors. Two screws are located on each connector to ensure that connections remain secure.
Page 285 IEEE-488 cables. Available shielded cables from Keithley are Models 7007-1 and 7007-2. To connect the Model 2750 to the IEEE-488 bus, follow these steps: Line up the cable connector with the connector located on the rear panel. The con- nector is designed so it will fit only one way.
Page 286: General Bus Commands
Goes into effect when next addressed to listen. Goes into talker and listener idle states. LOCAL key locked out. Cancel remote; restore Model 2750 front panel operation. Cancel remote; restore front panel operation for all devices. Returns all devices to known conditions.
Page 287: Ren (Remote Enable)
MEASure? IFC (interface clear) The IFC command is sent by the controller to place the Model 2750 in the local, talker, lis- tener idle states. The unit responds to the IFC command by canceling front panel TALK or LSTN lights, if the instrument was previously placed in one of these states.
Page 288: Dcl (Device Clear)
DCL. GET (group execute trigger) GET is a GPIB trigger that is used as a trigger event to control operation. The Model 2750 reacts to this trigger if it is the programmed trigger control source. The following com-...
Page 289: Front Panel Gpib Operation
Clear) command. LSTN This indicator is on when the Model 2750 is in the listener active state, which is activated by addressing the instrument to listen with the correct MLA (My Listen Address) com- mand. LSTN is off when the unit is in the listener idle state. Place the unit in the listener idle state by sending UNL (Unlisten), addressing it to talk, or sending IFC (Interface Clear) command over the bus.
Page 290: Local Key
Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-11 You can program the instrument to generate a service request (SRQ) when one or more errors or conditions occur. When this indicator is on, a service request has been generated. This indicator stays on until the serial poll byte is read or all the conditions that caused SRQ have been cleared.
Page 291 10-12 Remote Operations Model 2750 Multimeter/Switch System User’s Manual These brackets indicate that IMMediate is implied (optional) and does not have to be used. Thus, the above command can be sent in one of two ways: INITiate INITiate:IMMediate Notice that the optional command is used without the brackets. When using optional com- mand words in your program, do not include the brackets.
Page 292: Query Commands
Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-13 Angle brackets < > Angle brackets (< >) are used to denote a parameter type. Do not include the brackets in the program message. For example: RATio <b> The <b> indicates a Boolean-type parameter is required.
Page 293: Long-Form And Short-Form Versions
10-14 Remote Operations Model 2750 Multimeter/Switch System User’s Manual Long-form and short-form versions An SCPI command word can be sent in its long-form or short-form version. The command subsystem tables in Section 15 provide the long-form version. However, the short-form version is indicated by upper case characters.
Page 294: Program Messages
Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-15 Program messages A program message is made up of one or more command words sent by the computer to the instrument. Each common command is a three letter acronym preceded by an asterisk (*).
Page 295 10-16 Remote Operations Model 2750 Multimeter/Switch System User’s Manual Command path rules • Each new program message must begin with the root command, unless it is optional (e.g., [SENSe]). If the root is optional, simply treat a command word on the next level as the root.
Page 296: Response Messages
10-15), the multiple response messages for all the queries are sent to the computer when the Model 2750 is addressed to talk. The responses are sent in the order the query commands were sent and are separated by semicolons (;). Items within the same query are separated by commas (,).
Page 297: Rs-232 Interface Operation
EXIT. The next command to send buffer data (i.e., TRACe:DATA?) will start at the begin- ning, rather than where the transmission was halted. Baud rate The baud rate is the rate at which the Model 2750 multimeter and the programming termi- nal communicate. Choose one these available rates: •...
Page 298: Signal Handshaking (Flow Control)
XonXoFF is the FACT and *RST default flow control setting. If NONE is the selected flow control, then there will be no signal handshaking between the controller and the Model 2750. Data will be lost if transmitted before the receiving device is ready.
Page 299: Selecting And Configuring Rs-232 Interface
10-20 Remote Operations Model 2750 Multimeter/Switch System User’s Manual Selecting and configuring RS-232 interface After selecting (enabling) the RS-232 interface, you will then set the baud rate, flow con- trol, and terminator. Press the SHIFT key and then the RS-232 key. The RS 232 ON or RS 232 OFF message will be displayed.
Page 300 Model 2750 Multimeter/Switch System User’s Manual Remote Operations 10-21 Figure 10-4 RS-232 interface connector Rear Panel Connector...
Page 301: Error Messages
10-22 Remote Operations Model 2750 Multimeter/Switch System User’s Manual Table 10-2 RS-232 connector pinout Pin number Description No connection TXD, transmit data RXD, receive data No connection GND, signal ground Not used RTS, ready to send CTS, clear to send No connection CTS and RTS are not used.
Page 302: Status Structure
Status Structure • Overview — Provides an operational overview of the status structure for the Model 2750. • Clearing registers and queues — Covers the actions that clear (reset) registers and queues. • Programming and reading registers — Explains how to program enable registers and read any register in the status structure.
Page 303: Overview
Status Structure Model 2750 Multimeter/Switch System User’s Manual Overview The Model 2750 provides a series of status registers and queues allowing the operator to monitor and manipulate the various instrument events. The status structure is shown in Figure 11-1. The heart of the status structure is the Status Byte Register. This register can be read by the user’s test program to determine if a service request (SRQ) has occurred,...
Page 304 Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-3 Figure 11-1 Model 2750 status register structure Questionable Questionable Questionable Condition Event Event Enable Register Register Register & & & & Temp Temp Temp Temperature Summary & & & Logical &...
Page 305: Clearing Registers And Queues
Model 2750 Multimeter/Switch System User’s Manual Clearing registers and queues When the Model 2750 is turned on, the bits of all registers in the status structure are cleared (reset to 0), and the two queues are empty. Commands to reset the event and event...
Page 306: Programming And Reading Registers
Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-5 Programming and reading registers Programming enable registers The only registers that can be programmed by the user are the enable registers. All other registers in the status structure are read-only registers. The following explains how to ascertain the parameter values for the various commands used to program enable registers.
Page 307: Reading Registers
11-6 Status Structure Model 2750 Multimeter/Switch System User’s Manual Reading registers Any register in the status structure can be read by using the appropriate query (?) com- mand. The following explains how to interpret the returned value (response message). The...
Page 308: Status Byte Register
Service (RQS) bit or the Master Summary Status (MSS) bit: • When using the serial poll sequence of the Model 2750 to obtain the status byte (a.k.a. serial poll byte), B6 is the RQS bit. See “Serial polling and SRQ,”...
Page 309: Service Request Enable Register
Typically, SRQs are managed by the serial poll sequence of the Model 2750. If an SRQ does not occur, bit B6 (RQS) of the Status Byte Register will remain cleared, and the pro- gram will simply proceed normally after the serial poll is performed.
Page 310: Status Byte And Service Request Commands
1. The last command reads the Status Byte Register. Keep in mind that you have to address the Model 2750 to talk after sending a query command. To determine the exact nature of the error, you will have to read the Error Queue (see “Queues,”...
Page 311 11-10 Status Structure Model 2750 Multimeter/Switch System User’s Manual ' $INCLUDE: 'ieeeqb.bi' ' Clear PC output screen CONST addr = 16 ' Set instrument address. ' Init GPIB. CALL initialize(21, 0) CALL transmit("unt unl listen " + STR$(addr) + " sdc unl", status%) ' Send Device Clear.
Page 312: Status Register Sets
Bit B0, Operation Complete (OPC) — Set bit indicates that all pending selected • device operations are completed and the Model 2750 is ready to accept new com- mands. This bit only sets in response to the *OPC? query command. See Section 12 for details on *OPC and *OPC?.
Page 313 Bits B8, Filter Settled (Filt) — Set bit indicates that the filter has settled or the fil- • ter is disabled. Bit B9 — Not used. • Bit B10, Idle State (Idle) — Set bit indicates the Model 2750 is in the idle state. • Bits B11 through B15 — Not used. •...
Page 314 Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-13 Figure 11-5 Operation event status Operation Idle Filt Trig Meas Condition (B15 - B11) (B10) (B9) (B8) (B7) (B6) (B5) (B4) (B3) (B2) (B1) (B0) Register Operation Idle Filt Trig Meas...
Page 315 11-14 Status Structure Model 2750 Multimeter/Switch System User’s Manual • Bit B6, Buffer Notify (BN) — Set bit is a notification that the user-specified num- ber of readings have been stored in the buffer. The TRACe:NOTify command spec- ifies the number of stored readings that will set this bit (see Section 6 for details).
Page 316 Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-15 Figure 11-6 Measurement event status Measurement Condition — (B15) (B14) (B13) (B12) (B11) (B10) (B9) (B8) (B7) (B6) (B5) (B4) (B3) (B2) (B1) (B0) Register Measurement — Event Register (B15) (B14)
Page 317 11-16 Status Structure Model 2750 Multimeter/Switch System User’s Manual Questionable event register The used bits of the Questionable Event Register (Figure 11-7) are described as follows: • Bits B0 through B3 — Not used. • Bit B4, Temperature Summary (Temp) — Set bit indicates that an invalid refer- ence junction measurement has occurred for thermocouple temperature measurements.
Page 318 Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-17 Figure 11-7 Questionable event status Questionable Warn Temp Condition (B15) (B14) (B13 - B9) (B7 - B5) (B4) (B3 - B0) (B8) Register Questionable Warn Temp Event (B15) (B14) (B13 - B9)
Page 319: Condition Registers
For example, while the Model 2750 is in the idle state, bit B10 (Idle) of the Operation Condition Register will be set. When the instrument is taken out of idle, bit B10 clears.
Page 320: Event Enable Registers
Programming example — program and read register set The following command sequence programs and reads the measurement register set. Keep in mind that the Model 2750 has to be addressed to talk after a query command. STAT:MEAS:ENAB 512 ' Enable BFL (buffer full).
Page 321: Queues
Output Queue is considered cleared when it is empty. An empty Output Queue clears the MAV bit in the Status Byte Register. A message is read from the Output Queue by addressing the Model 2750 to talk after the appropriate query is sent.
Page 322 Model 2750 Multimeter/Switch System User’s Manual Status Structure 11-21 On power-up, all error messages are enabled and will go into the Error Queue as they occur. Status messages are not enabled and will not go into the queue. As listed in Table 11-6, there are commands to enable and/or disable messages.
Page 323 11-22 Status Structure Model 2750 Multimeter/Switch System User’s Manual...
Page 324: Common Commands
Common Commands...
Page 325 Returns the model numbers of the switching modules installed in the Model 2750. Returns “NONE” if a slot is empty. *RCL <NRf> Recall command Returns Model 2750 to the user-saved setup (0, 1, or 2). *RST Reset command Returns Model 2750 to the *RST default conditions.
Page 326 ‘ Sends the OPC command. *ESR? ‘ Reads the Standard Event Status Register. After addressing the Model 2750 to talk, the returned value of 0 denotes that the bit (bit 0) is not set indicating that the :INITiate operation is not complete. ABORt ‘...
Page 327 When used with the Initiate Immediately command (:INITiate), a “1” will not be placed into the Output Queue until the Model 2750 goes back into the idle state. The :INIT com- mand operation is not considered finished until the Model 2750 goes back into the idle state.
Page 328 Query installed switching modules Use this query command to determine which switching modules are installed in the Model 2750. For example, if a Model 7703 is installed in slot 1, and the other slots are empty, the response message will look like this: 7703, NONE, NONE, NONE, NONE Note that the model number of an installed pseudocard is returned in the same manner.
Page 329 G *TRG — trigger Send bus trigger to Model 2750 Use the *TRG command to issue a GPIB trigger to Model 2750. It has the same effect as a group execute trigger (GET). Use the *TRG command as an event to control operation. Model 2750 reacts to this trigger if BUS is the programmed arm control source.
Page 330 The INITiate commands remove the Model 2750 from the idle state. The device opera- tions of :INITiate are not considered complete until the Model 2750 returns to idle. By sending the *WAI command after the INITiate command, all subsequent commands will not execute until the Model 2750 goes back into idle.
Page 331 12-8 Common Commands Model 2750 Multimeter/Switch System User’s Manual...
Page 332: Scpi Signal Oriented Measurement Commands
SCPI Signal Oriented Measurement Commands...
Page 333 Table 13-1 Signal oriented measurement command summary Command Description CONFigure:<function> [<rang>], [<res>], [<clist>] Places the Model 2750 in a “one-shot” measurement mode for the specified function. FETCh? Requests the latest reading. READ? Performs an ABORt, INITiate, and a FETCh?.
Page 334: Configure: [], [], []
Model 2750 Multimeter/Switch System User’s Manual SCPI Signal Oriented Commands 13-3 CONFigure:<function> [<rang>], [<res>], [<clist>] CONFigure:VOLTage[:DC] [<rang>], [<res>], [<clist>] Configure DCV CONFigure:VOLTage:AC [<rang>], [<res>], [<clist>] Configure ACV CONFigure:CURRent[:DC] [<rang>], [<res>], [<clist>] Configure DCI CONFigure:CURRent:AC [<rang>], [<res>], [<clist>] Configure ACI Configure Ω2 CONFigure:RESistance [<rang>], [<res>], [<clist>]...
Page 335 The count values of the Trigger Model are set to one. • The delay of the Trigger Model is set to zero. • The Model 2750 is placed in the idle state. • All math calculations are disabled. • Buffer operation is disabled. A storage operation presently in pro- cess will be aborted.
Page 336: Fetch
Description This command requests the latest post-processed reading. After sending this command and addressing the Model 2750 to talk, the reading is sent to the computer. This command does not affect the instrument setup. This command does not trigger a measurement. The command simply requests the last available reading.
Page 337 Buffer operation is covered in Section The buffer of the Model 2750 is nonvolatile. Therefore, readings stored in the buffer are not lost when the instrument is turned off, or when *RST or SYSTem:PRESet is sent. When writing test programs that perform multi-sample measurements (SAMPle:COUNTt >1), you may want to add the TRACe:CLEar...
Page 338: Measure:? [], [], []
Model 2750 Multimeter/Switch System User’s Manual SCPI Signal Oriented Commands 13-7 MEASure:<function>? [<rang>], [<res>], [<clist>] MEASure:VOLTage[:DC]? [<rang>], [<res>], [<clist>] Measure DCV MEASure:VOLTage:AC? [<rang>], [<res>], [<clist>] Measure ACV MEASure:CURRent[:DC]? [<rang>], [<res>], [<clist>] Measure DCI MEASure:CURRent:AC? [<rang>], [<res>], [<clist>] Measure ACI Measure Ω2 MEASure:RESistance? [<rang>], [<res>], [<clist>]...
Page 339 13-8 SCPI Signal Oriented Commands Model 2750 Multimeter/Switch System User’s Manual When a MEASure? command is sent, the specified function is selected. If specified, range and resolution will also set. All other instrument set- tings related to the selected function are reset to the *RST defaults.
Page 340: Format And Miscellaneous System Commands
FORMat and Miscellaneous SYSTem Commands • FORMat commands — Covers the SCPI commands to configure the format that readings are sent over the bus. • Miscellaneous SYSTem commands — Covers miscellaneous SYSTem commands.
Page 341: Format Commands
14-2 FORMat and Misc SYSTem Commands Model 2750 Multimeter/Switch System User’s Manual FORMat commands The commands in this subsystem are used to select the format for transferring data, , over the bus. Table 14-1 Table 14-1 SCPI commands — data format...
Page 342 Model 2750 Multimeter/Switch System User’s Manual FORMat and Misc SYSTem Commands 14-3 ASCII data format The ASCII data format is in a direct readable form for the operator. Most programming languages easily convert ASCII mantissa and exponent to other formats. However, some speed is compromised to accommodate the conversion.
Page 343 14-4 FORMat and Misc SYSTem Commands Model 2750 Multimeter/Switch System User’s Manual Figure 14-2 IEEE-754 data formats Header Byte 1 Byte 2 Byte 3 Byte 4 s = sign bit (0 = positive, 1 = negative) e = exponent bits (8) f = fraction bits (23) Normal byte order shown.
Page 344: Format:elements
TRACe:TSTamp:FORMat ' Select timestamp format; ABSolute or DELTa. Reading number — The reading counter starts at zero when the Model 2750 is turned on. When returning buffer readings using TRACe:DATA?, each reading will be referenced to the first reading, which is #0.

Page 345: Format:border
14-6 FORMat and Misc SYSTem Commands Model 2750 Multimeter/Switch System User’s Manual Limits — For the ASCII data format, limit test results are returned as a 4-bit binary num- ber “abcd” where: a = High limit 2 b = Low limit 2...

Page 346: Miscellaneous System Commands
*SYST:PRES, which is a slow responding command. Details on *OPC and *OPC? are provided in Section SYSTem:VERSion Read the version of the SCPI standard being used by Model 2750. Example response mes- sage: 1996.0. SYSTem:KEY <NRf> Parameters...
Page 347: System:beeper[:State]
Model 2750 Multimeter/Switch System User’s Manual The queue for the :KEY? query command can only hold one key-press. When :KEY? is sent and Model 2750 is addressed to talk, the key-press code number for the last key “pressed” is sent to the computer.

Page 348: Scpi Reference Tables
SCPI Reference Tables...
Page 349: Reference Tables
NOTE The commands listed in the following tables pertain to operation of the Model 2750 and the Model 7700 switching module. For commands that are unique to operation of other switching modules, refer to the packing list that was included with the module.
Page 350 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-3 Table 15-1 CALCulate command summary Default Command Description parameter SCPI CALCulate[1] Subsystem to control CALC 1: Sec 5 :FORMat <name> Select math format (NONE, MXB, PERCent, or PERCent [<, clist>] RECiprocal).
Page 351 15-4 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-1 (continued) CALCulate command summary Default Command Description parameter SCPI CALCulate3 Subsystem to control CALC 3 (limit test): Sec 9 :MLIMit Path for master limit command: :LATChed <b> Enable or disable master limit latch.
Page 352 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-5 Table 15-1 (continued) CALCulate command summary Default Command Description parameter SCPI CALCulate3 :LIMit2 Path to control LIMIT 2 test: :UPPer Path to configure upper limit: [:DATA] <n> Set upper limit (-4294967295 to [, <clist>]...
Page 353 15-6 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-2 DISPlay command summary Default Command Description parameter SCPI DISPlay (see Note) Sec 1 [:WINDow[1]] :TEXT Path to control user text messages. :DATA <a> Define ASCII message “a” (none) (up to 12 characters).
Page 354 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-7 Table 15-4 ROUTe command summary Default Command Description parameter SCPI ROUTe :MONitor <clist> Specify one channel to be monitored. Sec 7 :STATe <b> Enable or disable channel monitoring. :STATe? Query state of channel monitoring.
Page 355 15-8 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-4 (continued) ROUTe command summary Default Command Description parameter SCPI ROUTe :SCAN Path to configure scan: Sec 7 [:INTernal] <clist> Specify list of channels to be scanned. [:INTernal]? Query scan list.
Page 356 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-9 Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI :DELay <NRf> [, <clist>] Set delay between the two measurements in seconds (0 to 99999.999). :DELay? [<clist>] Query delay.
Page 357 15-10 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :VOLTage:AC Path to configure AC voltage. Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 358 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-11 Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :CURRent[:DC] Path to configure DC current. Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 359 15-12 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :CURRent:AC Path to configure AC current. Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 360 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-13 Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :RESistance Path to configure resistance. Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 361 15-14 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :FRESistance Path to configure four-wire resistance. Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 362 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-15 Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :TEMPerature Path to configure temperature: Sec 3 :APERture <NRf> Set integration rate in seconds (60Hz, (Note 2) Sec 4 [, <clist>]...
Page 363 15-16 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :TEMPerature :TCouple Path to configure thermocouple: Sec 3 :TYPE <type> [, <clist>] Select T/C type (J, K, T, E, R, S, B, N).
Page 364 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-17 Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :FREQuency Path to configure frequency. Sec 3 :APERture <NRf> Sets gate time for frequency Sec 4 [, <clist>] measurements in seconds (0.01 to 1.0).
Page 365 15-18 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-5 (continued) SENSe command summary Default Command Description parameter SCPI [SENSe[1]] :CONTinuity Path to configure continuity test: Sec 3 :THReshold <NRf> Set threshold resistance in ohms (1 to 1000).
Page 366 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-19 Table 15-6 STATus command summary Default Command Description parameter SCPI STATus (Note 1) Sec 11 :MEASurement Path to control measurement event registers: [:EVENt]? Read the event register. (Note 2) :ENABle <NRf>...
Page 367 15-20 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-7 SYSTem command summary Default Command Description parameter SCPI SYSTem :PRESet Return to :SYST:PRES defaults. Sec 14 :POSetup <name> Select power-on setup: (RST, PRESet, SAV0, Sec 1 SAV1, or SAV2).
Page 368 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-21 Table 15-7 (continued) SYSTem command summary Default Command Description parameter SCPI SYSTem 1, 2 :CARD Path to query switching module in specified slot. For the following :CARD commands, <NRf> = slot number for module.
Page 369 15-22 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-7 (continued) SYSTem command summary Default Command Description parameter SCPI SYSTem :END Request highest numbered digital output channel; 0 = digital input not supported. :SNOpen? Query whether card is “single no-open” type (i.e., 7711): 1 = yes, 0 = no.
Page 370 :CARD command word (i.e., SYST:CARD1:SNUM?). In order to make the Model 2750 compatible with Model 2700 operation, the :CARD command for the Model 2750 will accept the syntax for slots 1 and 2. 3. If a pseudocard is installed in the slot, the message "????????" will be returned when querying the serial number or firmware revision.
Page 371 15-24 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-8 TRACe command summary Default Command Description parameter* SCPI TRACe|:DATA Use TRACe or DATA as root command. Sec 6 :CLEar Path to clear the buffer. [:IMMediate] Clear the buffer.
Page 372 Model 2750 Multimeter/Switch System User’s Manual SCPI Reference Tables 15-25 Table 15-9 Trigger command summary Default Command Description parameter SCPI INITiate Subsystem command path: Sec 8 [:IMMediate] Initiate one trigger cycle. :CONTinuous <b> Enable or disable continuous initiation. (Note 1) :CONTinuous? Query continuous initiation.
Page 373 15-26 SCPI Reference Tables Model 2750 Multimeter/Switch System User’s Manual Table 15-10 UNIT command summary Default Command Description parameter SCPI UNIT :TEMPerature <name> Select temperature units (C, CEL, F, Sec 3 FAR, or K). :TEMPerature? Query temperature units. :VOLTage Path to configure voltage units.
Page 374: Model 7700 Connection Guide
Model 7700 Connection Guide...
Page 375: Card Configuration - Schematic
AMP and LO common connections to the DMM are also provided. Channel 23 (2W/4W Configuration), Channel 24 (Sense Isolation), and Channel 25 (Input Isolation) are normally automatically configured by the 2750 for system channel opera- tion. However, by using multiple channel operation (refer to...
Page 376 Model 2750 Multimeter/Switch System User’s Manual Model 7700 Connection Guide Figure B-1 Simplified schematic for Model 7700 Input Sense HI Cold Junction Ref x3 Channel 1 Channel 25 (See Note) (Channels 2–9) Backplane Isolation Channel 10 Input Channel 23 2-Pole (Open)
Page 377: Connections And Wiring
For details to safely make high energy measurements, see “High energy circuit safety precautions,” page 3-3. As described in the International Electrotechnical Commission (IEC) Standard IEC 664, the Model 2750 is Installation Category I and must not be connected to mains.
Page 378: Screw Terminals
Model 2750 Multimeter/Switch System User’s Manual Model 7700 Connection Guide Screw terminals Figure B-2 shows how to access the screw terminals on the Model 7700. Channel designa- tions for the screw terminals are contained in Figure B-3. Figure B-2 Screw terminal access...
Page 379: Wiring Procedure
Model 7700 Connection Guide Model 2750 Multimeter/Switch System User’s Manual Figure B-3 Model 7700 screw terminal channel designations INPUT SENSE CH10 Cable Tie Holes CH10 INPUT (V, 2-WIRE) SENSE (OHMS, 4-WIRE) CH17 CH18 CH19 CH20 CH21 CH22 CH11 CH12 CH13...
Page 380: Typical Connections
Model 2750 Multimeter/Switch System User’s Manual Model 7700 Connection Guide Figure B-4 Wire dressing Cable INPUT V, 2-WIRE) CH10 INPUT (V, 2-WIRE) Supplementary SENSE Insulation (OHMS, 4-WIRE) CH17 CH18 CH19 CH20 CH21 CH22 CH11 CH12 CH13 CH14 CH15 CH16 Typical connections...
Page 381 Model 7700 Connection Guide Model 2750 Multimeter/Switch System User’s Manual Figure B-5 Thermocouple connections Channel 1 (Channels 2–19) Thermocouple Channel 20 Figure B-6 Ω2-Wire and thermistor connections Channel 1 Resistor or (Channels 2–19) Thermistor Channel 20...
Page 382 Model 2750 Multimeter/Switch System User’s Manual Model 7700 Connection Guide Figure B-7 Ω4-Wire and RTD connections Resistor or Channel 1 4-Wire RTD (Channels 2–9) Resistor or Channel 10 4-Wire RTD Channel 11 (Channels 12–19) Channel 20 Figure B-8 Current connections (AC or DC)
Page 383: Connection Log
B-10 Model 7700 Connection Guide Model 2750 Multimeter/Switch System User’s Manual Figure B-9 Voltage connections (DC or AC) DC Voltage AC Voltage Channel 1 (Channels 2–19) Channel 20 Connection log Make a copy of Table B-1 and affix it to the cover of the Model 7700. Use this to record...
Page 384 Model 2750 Multimeter/Switch System User’s Manual Model 7700 Connection Guide B-11 Table B-1 Connection log Model 7700 Channel Color Description AMPS COM INPUT SENSE CH10 CH11 CH12 CH13 CH14 CH15 CH16 CH17 CH18 CH19 CH20 AMPS 21 AMPS 22...
Page 385 B-12 Model 7700 Connection Guide Model 2750 Multimeter/Switch System User’s Manual...
Page 386: Status And Error Messages
Status and Error Messages...
Page 387 Status and Error Messages Model 2750 Multimeter/Switch System User’s Manual Table C-1 Status and error messages Number Description Event -440 Query unterminated after indefinite response -430 Query deadlocked -420 Query unterminated -410 Query interrupted -363 Input buffer overrun -350 Queue overflow...
Page 388 Model 2750 Multimeter/Switch System User’s Manual Status and Error Messages Table C-1 (continued) Status and error messages Number Description Event -148 Character data not allowed -144 Character data too long -141 Invalid character data -140 Character data error -128 Numeric data not allowed...
Page 389 Status and Error Messages Model 2750 Multimeter/Switch System User’s Manual Table C-1 (continued) Status and error messages Number Description Event +101 Operation complete +121 Device calibrating +122 Device settling +123 Device ranging +124 Device sweeping +125 Device measuring +126 Device calculating...
Page 390 Model 2750 Multimeter/Switch System User’s Manual Status and Error Messages Table C-1 (continued) Status and error messages Number Description Event Calibration messages: +400 10vdc zero error +401 100vdc zero error +402 10vdc full scale error +403 -10vdc full scale error...
Page 391 Status and Error Messages Model 2750 Multimeter/Switch System User’s Manual Table C-1 (continued) Status and error messages Number Description Event +456 1 vac zero error +457 1 vac full scale error +458 1 vac noise error +459 10 vac zero error...
Page 392 Model 2750 Multimeter/Switch System User’s Manual Status and Error Messages Table C-1 (continued) Status and error messages Number Description Event +496 1 4-w dckt Ioff zero error +497 1 4-w dckt Ion zero error +498 1 4-w dckt Ion full scale error...
Page 393 Status and Error Messages Model 2750 Multimeter/Switch System User’s Manual...
Page 394 Signal Processing Sequence and Data Flow...
Page 395: Signal Processing Sequence And Data Flow
With all the various features (filter, rel, math, ratio, channel average, buffer, etc.) of the Model 2750 disabled, the input signal is conditioned and measured (A/D conversion pro- cess). The reading is then displayed on the Model 2750.
Page 396: Signal Processing Using Instrument Features
Model 2750 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow Signal processing using instrument features Figure D-2 shows the processing sequence for an input signal with various instrument fea- tures enabled. If a feature is not enabled, the reading simply falls through to the next enabled feature or to the display.
Page 397 4-14. Output trigger pulse (VMC) An output trigger pulse from the Model 2750 can be used to trigger an external instrument to perform an operation. In general, a trigger pulse is output at this point in flow chart for each processed reading.
Page 398 The reading that is applied to the Limits block in the flow chart is not modified and is the reading that is displayed on the Model 2750. With Limits enabled, the reading is tested against two sets of high and low limits. Along with the displayed reading, annunciators and messages are used to indicate the result of the limits testing.
Page 399: Signal Processing Using Ratio Or Ch Avg
Signal Processing Sequence and Data Flow Model 2750 Multimeter/Switch System User’s Manual Signal processing using Ratio or Ch Avg With a switching module installed, the ratio or average of two channels can be calculated. Figure D-3 shows where Ratio or Ch Avg is calculated in the signal processing sequence.
Page 400: Data Flow (Remote Operation
Model 2750 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow Data flow (remote operation) Remote operation can be used with triggering configured to perform a specified number of measurements and then stop. The various read commands (SENS:DATA?, FETCh?, READ?, MEAS?, CALC2:DATA?, TRACe:DATA?, and CALC1:DATA?) return the data array(s) acquired during the measurement cycle.
Page 401: Sense And Sample Buffer
Signal Processing Sequence and Data Flow Model 2750 Multimeter/Switch System User’s Manual NOTE For the following discussion, a “data array” is defined as the group of data ele- ments that are included with each measured reading. Each data array includes...
Page 402: [Sens[1]]:Data[:Latest]
Model 2750 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow [SENS[1]]:DATA[LATest]? [SENS[1]]:DATA:FRESh? These commands are used to return (read) the last processed data array stored in the sam- ple buffer. [SENS[1]]:DATA[:LATest]? This command returns (reads) one data array. It returns the last processed data array stored in the sample buffer.
Page 403 D-10 Signal Processing Sequence and Data Flow Model 2750 Multimeter/Switch System User’s Manual NOTE For more information on FETCh?, READ? and MEASure?, see Section “SCPI Signal Oriented Measurement Commands.” FETCh? With no Math function enabled, this command reads the data arrays stored in the sample buffer.
Page 404: Calc3:Lim1:Fail
Model 2750 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow D-11 CALC[1]:DATA[:LATest]? CALC[1]:DATA:FRESh? These two commands are similar to the LATest? and FRESh? commands for the SENSe1 subsystem, except that returned data arrays are the result of the math calculation. See [SENS[1]]:DATA[:LATest]? and [SENS[1]]:DATA:FRESh? for details on the differences between LATest? and FRESh?.
Page 405: Calc2:Imm
D-12 Signal Processing Sequence and Data Flow Model 2750 Multimeter/Switch System User’s Manual CALC2:IMM? CALC2:IMM CALC2:DATA? Statistical information (minimum, maximum, mean, standard deviation, and peak-to-peak) is available for the readings stored in the buffer (data store). When the desired calculation...
Page 406: Scanning
Model 2750 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow D-13 Scanning For remote operation, scanning is normally performed with continuous initiation disabled (INIT:CONT OFF). The sample count (SAMP:COUNt) specifies the number of channels to scan and store in the buffers (sample buffer and data store), and the trigger count (TRIG:COUNt) specifies the number of scans to perform.
Page 407 D-14 Signal Processing Sequence and Data Flow Model 2750 Multimeter/Switch System User’s Manual...
Page 408: Measurement Considerations
Measurement Considerations...
Page 409: Thermoelectric Potentials
Model 2750 Multimeter/Switch System User’s Manual Measurement considerations Low-level voltage measurements made using the Model 2750 can be adversely affected by various types of noise or other unwanted signals that can make it very difficult to obtain accurate voltage readings. Some of the phenomena that can cause unwanted noise include thermoelectric effects (thermocouple action), source resistance noise, magnetic fields, and radio frequency interference.
Page 410: Thermoelectric Generation
Model 2750 Multimeter/Switch System User’s Manual Measurement Considerations Thermoelectric generation Figure E-1 shows a representation of how thermal EMFs are generated. The test leads are made of the A material, while the source under test is the B material. The temperatures...
Page 411: Minimizing Thermal Emfs
Even if all reasonable precautions are taken, some residual thermal offsets may still be present. These offsets can be minimized by using the Model 2750 Relative feature to null them out. To do so, place the instrument on the 3mV range and short the end of the con- necting cable nearest the measured source (first disconnect the cable from the source to avoid shorting out the source).
Page 412: Source Resistance Noise
Source resistance noise Noise present in the source resistance is often the limiting factor in the ultimate resolution and accuracy of Model 2750 measurements. The following paragraphs discuss the genera- tion of Johnson noise as well as ways to minimize such noise.
Page 413: Magnetic Fields
Fields can be produced by various sources such as the AC power line voltage. Large inductors such as power transformers can generate substantial magnetic fields, so care must be taken to keep the Model 2750 voltage source and connecting cables a good dis- tance away from these potential noise sources.
Page 414 Model 2750 Multimeter/Switch System User’s Manual Measurement Considerations Ground loops When two or more instruments are connected together, care must be taken to avoid unwanted signals caused by ground loops. Ground loops usually occur when sensitive instrumentation is connected to other instrumentation with more than one signal return path such as power line ground.
Page 415: Ground Loops
Here, only one instrument is connected to power line ground. Ground loops are not normally a problem with instruments like the Model 2750 that have isolated LO terminals. However, all instruments in the test setup may not be designed in this manner.
Page 416: Shielding
Model 2750 Multimeter/Switch System User’s Manual Measurement Considerations Shielding WARNING Do not float input LO more than 30V rms, 42.4V peak above earth ground with an exposed shield connected to input LO. To avoid a pos- sible shock hazard, surround the LO shield with a second safety shield that is insulated from the inner shield.
Page 417: Meter Loading
Percent error ------------------ - From the above equation, it is obvious that the input resistance of the Model 2750 must be at least 999 times the value of source resistance if loading error is to be kept to within 0.1%.
Page 418: Temperature Equations
Temperature Equations Thermocouple equation — Documents the ITS-90 inverse function polynomial • and the coefficients to calculate thermocouple temperature. • Thermistor equation — Documents the Steinhart-Hart equation which is used to calculate thermistor temperature. • RTD equation — Documents the Callendar-Van Dusen equation which is used to calculate the temperature vs.
Page 419: Thermocouple Equation
Model 2750 Multimeter/Switch System User’s Manual Thermocouple equation The Model 2750 uses the ITS-90 inverse function coefficients for the polynomial to calcu- late thermocouple temperature. The Model 2750 measures the thermocouple voltage, and then calculates temperature (in °C) as follows: E + c ...
Page 420 Model 2750 Multimeter/Switch System User’s Manual Temperature Equations Table F-2 Type E inverse function polynomial -200°C to 0°C 0°C to 1,000°C (-8,825µV to 0µV) (0µV to 76,373µV) 1.697 728 8 × 10 1.705 703 5 × 10 -4.351 497 0 × 10 -2.330 175 9 ×...
Page 421 Temperature Equations Model 2750 Multimeter/Switch System User’s Manual Table F-4 Type K inverse function polynomial -200°C to 0°C 0°C to 500°C 500°C to 1,372°C (-5,891µV to 0µV) (0µV to 20,644µV) (20,644µV to 54,886µV) -1.318 058 × 10 2.517 346 2 × 10 2.508 355 2 ×...
Page 422 Model 2750 Multimeter/Switch System User’s Manual Temperature Equations Table F-6 Type R inverse function polynomial -50°C to 250°C 250°C to 1,200°C 1,064°C to 1,664.5°C 1,664.5°C to 1,768.1°C (-226µV to (1,923µV to (11,361µV to (19,739µV to 1,923µV) 13,228µV) 19,739µV) 21,103µV) 1.334 584 505 × 10 -8.199 599 416 ×...
Page 423: Thermistor Equation
Kelvin. lnR is the natural log of the measured resistance of the thermistor. A, B, and C are the curve fitting constants. The constants for the three thermistor types used by the Model 2750 are listed in Table F-9.
Page 424 Selecting a thermistor — The thermistor’s manufacturer’s specified curve fitting values (A, B, and C) may not be exactly the same as the ones used by the Model 2750. If they are not exactly the same, perform the following steps to select a thermistor to use with the...
Page 425: Rtd Equation
Temperature Equations Model 2750 Multimeter/Switch System User’s Manual RTD equation The temperature vs. resistance readings listed in the RTD reference tables are calculated using the Callendar-Van Dusen equation: [1 + AT + BT + CT (T-100)] where; R is the calculated resistance of the RTD is the known RTD resistance at 0°C...
Page 426 Model 2750 Multimeter/Switch System User’s Manual Temperature Equations C = -1 (0.00385)(0.10863) (1e-8) = -1 (0.000418)(1e-8) = - 4.18e-12 The resistance of the RTD at 100°C (R ) is then calculated as follows: [1 + AT + BT + CT (T-100)] = 100 {1 + [(0.00391)(100)] + [(-5.77e-7)(100...
Page 427 F-10 Temperature Equations Model 2750 Multimeter/Switch System User’s Manual...
Page 428: Ieee-488 Bus Overview
IEEE-488 Bus Overview...
Page 429: Introduction
IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual Introduction The IEEE-488 bus is a communication system between two or more electronic devices. A device can be either an instrument or a computer. When a computer is used on the bus, it serves as a supervisor of the communication exchange between all the devices and is known as the controller.
Page 430 Model 2750 Multimeter/Switch System User’s Manual IEEE-488 Bus Overview Figure G-1 IEEE-488 bus configuration To Other Devices Device 1 able to talk, listen, and control (computer) Data Bus Device 2 able to talk and listen 2750 Data Byte Transfer Control...
Page 431: Bus Lines
The IEEE-488 standards also include another addressing mode called secondary address- ing. Secondary addresses lie in the range of $60-$7F. Note, however, that many devices, including the Model 2750, do not use secondary addressing. Once a device is addressed to talk or listen, the appropriate bus transactions take place. For example, if the instrument is addressed to talk, it places its data string on the bus one byte at a time.
Page 432: Bus Management Lines
Model 2750 Multimeter/Switch System User’s Manual IEEE-488 Bus Overview Bus management lines The five bus management lines help to ensure proper interface control and management. These lines are used to send the uniline commands. ATN (Attention) — The ATN state determines how information on the data bus is to be interpreted.
Page 433: Bus Commands
IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual Once all NDAC and NRFD are properly set, the source sets DAV low, indicating to accept- ing devices that the byte on the data lines is now valid. NRFD will then go low, and NDAC will go high once all devices have accepted the data.
Page 434 Model 2750 Multimeter/Switch System User’s Manual IEEE-488 Bus Overview Table G-1 IEEE-488 bus command summary State of Command type Command ATN line Comments Uniline REN (Remote Enable) Set up devices for remote operation. Marks end of transmission. IFC (Interface Clear) Clears interface.
Page 435: Uniline Commands
IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual Uniline commands ATN, IFC, and REN are asserted only by the controller. SRQ is asserted by an external device. EOI may be asserted either by the controller or other devices depending on the direction of data transfer.
Page 436: Addressed Multiline Commands
ORing the address with $40. Talk commands are used to address devices to talk. SCG (Secondary Command Group) — Commands in this group provide additional addressing capabilities. Many devices (including the Model 2750) do not use these commands. Unaddress commands The two unaddress commands are used by the controller to remove any talkers or listeners from the bus.
Page 437: Common Commands
G-10 IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual Common commands Common commands are commands that are common to all devices on the bus. These com- mands are designated and defined by the IEEE-488.2 standard. Generally, these commands are sent as one or more ASCII characters that tell the device to perform a common operation, such as reset.
Page 438: Command Codes
Model 2750 Multimeter/Switch System User’s Manual IEEE-488 Bus Overview G-11 Figure G-3 Command codes...
Page 439: Typical Command Sequences
G-12 IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual Typical command sequences For the various multiline commands, a specific bus sequence must take place to properly send the command. In particular, the correct listen address must be sent to the instrument before it will respond to addressed commands.
Page 440: Ieee Command Groups
Model 2750 Multimeter/Switch System User’s Manual IEEE-488 Bus Overview G-13 IEEE command groups Command groups supported by the Model 2750 are listed in Table G-5. Common com- mands and SCPI commands are not included in this list. Table G-5 IEEE command groups...
Page 441: Interface Function Codes
Open collector bus drivers. No Extended Talker capability. No Extended Listener capability. The codes define Model 2750 capabilities as follows: SH (Source Handshake Function) — SH1 defines the ability of the instrument to initiate the transfer of message/data over the data bus.
Page 442 DC (Device Clear Function) — DC1 defines the ability of the instrument to be cleared (initialized). DT (Device Trigger Function) — DTI defines the ability of the Model 2750 to have read- ings triggered. C (Controller Function) — The instrument does not have controller capabilities (C0).
Page 443 G-16 IEEE-488 Bus Overview Model 2750 Multimeter/Switch System User’s Manual...
Page 444 Index Bandwidth 4-10 Basic measurements CONFigure:<function> [<rang>], [<res>], Basic Operation [<clist>] 13-3 overview DISPlay:ENABle 1-18 Best temperature sensor 3-25 DISPlay:TEXT:DATA 1-18 Buffer 2-1, 6-1, 7-26 DISPlay:TEXT:STATe 1-18 commands Front panel Symbols Auto clear Enabling/disabling *IDN? — identification query 12-3 overview 2-2, 6-2 *OPC —...
Page 445 CARD menu 1-19, 2-28 Crest factor 3-12 tree 2-30 Limitations 3-12 Case sensitivity 10-13 Current measurements (DCI and ACI) 3-14 Channel assignments 2-6, 7-3 AMPS fuse replacement (front panel AMPS input) 3-16 Channel average 5-16 Amps measurement procedure 3-15 Channel closing and opening 2-25 Connections 3-14...
Page 446 Dry circuit ohms (DRYCKT) 3-22 Connections 3-39 Dry circuit ohms applications 3-22 Front panel input 3-39 Dual independent multiplexers 2-23 Model 7700 switching module 3-39 Dual multiplexer application 2-24 Gate time 3-38 DUT test system procedure 3-40 Trigger level 3-38 Front and rear panel familiarization Front panel Eliminating ground loops...
Page 447 Minimizing source resistance noise Keyclick 1-16 Minimizing thermal EMFs Remote programming 1-17 Miscellaneous SYSTem commands 14-7 Model 2750 curve fitting constants for thermistors Model 7700 Line frequency 1-15 ¾2-Wire and Thermistor connections Line power connection 1-14 ¾4-Wire and RTD connections...
Page 448 Typical connections Pressing REL using rel commands Voltage connections (DC or AC) B-10 program and read register set Wire dressing programming example 11-19 Wiring procedure Program message terminator (PMT) 10-16 Monitor channel 7-18 Program messages 10-15 Monitor scan 7-35 Programming syntax 10-11 Monitor scan (analog trigger) 7-23...
Page 449 Ratio and channel average delay 5-20 Cable leakage 3-17 Ratio channel pairing 5-16 Front panel inputs 3-17 read error queue Model 7700 switching module 3-17 programming example 11-21 Shielding 3-17 Reading count Offset compensated ohms 3-20 Reading hold (autosettle) Enabling/disabling 3-21, 3-23 Readings Performing...
Page 450 fundamentals 4-wire RTDs 3-28 Scanning examples 7-32 Connections 3-28 External trigger scan 7-32 Thermocouple connections 3-28 SCPI Reference Tables 15-1 Thermistors 3-27 SCPI Signal Oriented Measurement Commands Thermocouples 3-25 13-1 Open thermocouple detection 3-27 Selecting GPIB and setting primary address Reference junctions 3-26 10-4...
Page 451 Type K inverse function polynomial Type N inverse function polynomial Type R inverse function polynomial Type S inverse function polynomial Type T inverse function polynomial Typical command sequences G-12 Using common and SCPI commands in the same message 10-16 Viewing closed channels 2-28 Voltage measurements (DCV and ACV) Connections...
Page 452 M E A S U R E C O N F I D E N C E Keithley Instruments, Inc. Corporate Headquarters • 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168 • 1-888-KEITHLEY • www.keithley.com 12/06...