Rs232 Interface - Remote Control; Safety; Operation; Rs-232 Cable - Hameg HM404-2.02 Manual

RS232 Interface - Remote Control

1. Y AMP ( Y amplifier)
Corrects trace position changes of more than 0.5 division in Y
direction, as a result of different attenuator settings in the
range from 5mV/div to 5V/div when the input is not grounded
but screened.
2. TRIGGER-AMP (trigger amplifier)
Compensates higher deviations of the trigger point (symbol)
caused by switch over between AC and DC trigger coupling in
condition internal triggering (Source: CH I or CH II), when a 50
kHz sine wave signal without DC content (AC input coupling
recommended) is applied.
The instrument automatically adjusts and stores the
adjustment values in a non volatile memory after calling the
item. A new adjustment may be necessary after the
temperature conditions have changed once again drastically.
RS232 Interface - Remote Control

Safety

Caution:
All terminals of the RS232 interface are galvanically
connected with the oscilloscope and subsequently
with protective (safety) earth potential.
Measurement on a high level reference potential is not
permitted and endangers operator, oscilloscope, interface
and peripheral devices.
In case of disregard of the safety warnings contained in this
manual, HAMEG refuses any liability regarding personal injury
and/or damage of equipment.

Operation

The oscilloscope is supplied with a serial interface for control
purposes. The interface connector (9 pole D- SUB female) is
located on the rear of the instrument. Via this bidirectional
port, the instrument parameter settings can be transmitted
to, or received from a PC.

RS-232 Cable

The maximum connecting cable length must be less then 3
meters and must contain 9 screened lines connected 1:1. The
oscilloscope RS232 connection (9 pole D-SUB female) is
determined as follows:
Pin
2 Tx data (data from oscilloscope to external device)
3 Rx data (data from external device to oscilloscope)
7 CTS (clear to send)
8 RTS (request to send)
5 Ground (reference potential - connected via the
oscilloscope's power cord with protective earth)
The maximum voltage swing at pin 2, 3, 7 and 8 is ± 12 Volt.
32

RS-232 protocol

N-8-2 (no parity bit, 8 data bits, 2 stop bits, RTS/CTS hardware
protocol).

Baud-Rate Setting

After the first POWER UP (switching on of the oscilloscope )
and the first command SPACE CR (20hex, 0Dhex) sent from
the PC, the baud rate is recognized and set automatically
between 110 baud and 115200 baud. The oscilloscope is then
switched over to REMOTE control mode. The oscilloscope
then transmits the RETURNCODE: 0 CR LF to the PC. In this
status all settings (with the exception of those functions
mentioned under "Controls and Readout") can be controlled
via the interface only.
The only ways to quit this status are:
• Switching the oscilloscope off,
or transmitting the command
• RM= 0 from the PC to the oscilloscope, or
• depressing the AUTO SET ( LOCAL ) pushbutton,
if in unlocked condition (command LK=1... was not sent)
After the remote state has been switched off the RM-LED is
dark.
Please note:
A minimum time must elapse between the commands
RM=1... (remote on) and RM=0... (remote off) and vice
versa.
The time can be calculated with the formula:
t min = 2x(1/baud rate) + 60µs.
If at the beginning no SPACE CR command is recognizable,
the oscilloscope pulls the TxD line low for approx. 0.2ms and
causes a break on the PC.

Data Communication

After successfully being set to remote control mode, the
oscilloscope is prepared for command reception.
Subject to change without notice