Related Manuals for ABB DATUM L150
Summary of Contents for ABB DATUM L150
- Page 1 DATUM L150/160 Operating Guide MODBUS (RTU) Communications Option ABB Instrumentation...
- Page 2 Use of this manual for any other purpose is specifically prohibited and its contents are not to be reproduced in full or part without prior approval of Technical Communications Department, ABB Instrumentation. Health and Safety To ensure that our products are safe and without risk to health, the following points must be noted: 1.
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Page 3: Table Of Contents
CONTENTS INTRODUCTION ................... 2 ELECTRICAL INSTALLATION ..............3 2.1 Host Computer Serial Communications ..........3 2.2 OPTO22 Boards for use with Personal Computers ......3 2.3 Two-wire and Four-wire Connection ............ 3 2.4 Pull-up and Pull-down Resistors ............6 2.5 Termination Resistor ................6 2.6 Serial Connections ................ -
Page 4: Introduction
1 INTRODUCTION This Operating Guide describes the DATUM L150/L160 MODBUS serial data communications option and must be used in conjunction with the standard User Guide ( IM/L150 or IM/L160 ) supplied with the instrument. Information. The MODBUS option provides the following facilities: •... -
Page 5: Electrical Installation
2 ELECTRICAL INSTALLATION This section describes the connection of serial data transmission cables between the master (host computer) and slave DATUM L150/L160 instruments on a MODBUS serial link. All connections other than those used for serial communication are shown in Section 5 of the relevant User Guide . - Page 6 …2 ELECTRICAL INSTALLATION 2.4 Pull-up and Pull-down Resistors – Figs. 2.1 and 2.2 To prevent false triggering of slaves when the master (host computer) is inactive, pull-up and pull-down resistors must be fitted to the RS422/485 interface in the host computer –...
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Page 7: Pull-Up And Pull-Down Resistors
2 ELECTRICAL INSTALLATION… …2.4 Pull-up and Pull-down Resistors Host Computer 1.8kΩ Pull-up Resistor 1.8kΩ Pull-down Tx– Resistor 1.8kΩ Pull-up Rx– Resistor 1.8kΩ Pull-down Resistor Fig. 2.2a Four-wire Operation – L150 Host Computer 9 10 11 12 13 1.8kΩ Pull-up Resistor Rx–... -
Page 8: Termination Resistor
…2 ELECTRICAL INSTALLATION 2.5 Termination Resistor – Fig. 2.3 For long transmission lines, a 120Ω termination resistor must be fitted to the last slave in the chain – see Fig. 2.3. Master First Slave Last Slave Rx– Tx– Host Computer Tx–... - Page 9 2 ELECTRICAL INSTALLATION …2.6 Serial Connections – Figs. 2.1 to 2.4 OPTO22 Adaptor Board Connections Tx– Rx– Rx– Tx– Screen Fig. 2.4 OPTO22 Board Connections...
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Page 10: Configuration
3.2 Setting the Serial Transmission Parameters – Fig. 3.1 Fig. 3.1 shows the display readouts and options available when defining the serial transmission rate and bit parity for DATUM L150/L160 instruments. Further detail on the procedures required to set each parameter are shown in Section 4.3 of the relevant User Guide. -
Page 11: Modbus Protocol
4 MODBUS PROTOCOL Information. • The DATUM L150/L160 operates as a MODBUS, Remote Terminal Unit (RTU) slave. • Parity checking – detects transmission errors in individual characters. • Cyclic redundancy checking – detects errors in the master messages and slave responses. -
Page 12: Modbus Function Codes
Title Read Read up to 16 consecutive discrete (Boolean) points Coil Status from a specific starting point. The DATUM L150/L160 returns zeros for points which do not contain defined data and NAKs* any request for point numbers greater than 60. -
Page 13: Modbus Functions
5 MODBUS FUNCTIONS This section shows typical examples of MODBUS function codes 01, 03, 05, 06, 08 and 16. Not all addressable parameters used in the examples which follow are valid for both instrument types – see Sections 7.1 and 7.2. 5.1 Read Coil Status –... -
Page 14: Read Holding Register - Function Code 03
…5 MODBUS FUNCTIONS 5.2 Read Holding Register – Function Code 03 5.2.1 Read Holding Register Query The Read Holding Register Query obtains the contents of up to eight holding registers in the addressed slave. Note. The data start register must contain the offset address of the first register to be accessed, e.g. -
Page 15: Force Single Coil - Function Code 05
5 MODBUS FUNCTIONS… 5.3 Force Single Coil – Function Code 05 5.3.1 Force Single Coil Query This message forces a single coil either ON or OFF. The data value 65,280 (FF00 HEX) sets the coil ON and the value zero turns it OFF. All other values are illegal and have no effect on coil status. -
Page 16: Preset Single Register - Function Code 06
…5 MODBUS FUNCTIONS Preset Single Register – Function Code 06 5.4.1 Preset Single Register Query The Preset Single Register Query modifies the contents of a holding register. Note. Function codes 05, 06 and 16 are the only messages that are recognized as valid for broadcast. -
Page 17: Loopback Test - Function Code 08
5 MODBUS FUNCTIONS… Loopback Test – Function Code 08 5.5.1 Loopback Test Query The Loopback Test Query tests the MODBUS system and does not affect the operation of the slave. Variations in the response may indicate faults in the MODBUS system. The information field contains two bytes for the designation of the diagnostic code followed by two bytes to designate the action to be taken. -
Page 18: Write Multiple Registers - Function Code 16
…5 MODBUS FUNCTIONS Write Multiple Registers – Function Code 16 5.6.1 Write Multiple Registers Query This message is used to change the contents of up to eight holding registers at a time. When used with slave address zero (broadcast mode) all slave controllers load the selected registers with the contents specified. -
Page 19: Exception Responses
6 EXCEPTION RESPONSES The exception response codes sent by the slave are shown in Table 6.1. When a slave detects one of these errors, it sends a response message to the master consisting of slave address, function code, error code and error check fields. Exception Exception Response Exception Response... -
Page 20: Addressable Parameters
7 ADDRESSABLE PARAMETERS 7.1 Coils Coil No. Variable Label Read/Write Limits/Values Process Variable Fail State 1 = Failed A/D Converter Fail State 1 = Failed Alarm State 1 1 = Active Alarm Indicator 1 1 = On Alarm State 2 1 = Active Alarm Indicator 2 1 = On... -
Page 21: Alarm Settings
7 ADDRESSABLE PARAMETERS …7.2 Registers 7.2.2 Alarm Settings Register Variable Label Read/Write Limits/Values 50 + 51 Alarm Trip 1 –9999 to 99999 52 + 53 Alarm Trip 2 –9999 to 99999 54 + 55 Alarm Trip 3 –9999 to 99999 0 = None Alarm Type 1 1 = High Process... - Page 22 NOTES...
- Page 23 Customer Support ABB Instrumentation provides a comprehensive after sales service via a Worldwide Service Organization. Contact one of the following offices for details on your nearest Service and Repair Centre. United Kingdom ABB Instrumentation Limited Tel: +44 (0)1480 475321 Fax: +44 (0)1480 470787 United States of America ABB Automation Inc.
- Page 24 The Company's policy is one of continuous product improvement and the right is reserved to modify the information contained herein without notice. © ABB 1999 Printed in UK (10.99) ABB Instrumentation Ltd ABB Automation Inc. ABB Kent-Taylor SpA St. Neots...