PST Michell Instruments Liquidew I.S., Руководство пользователя

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Liquidew I.S. User Manual
Michell Instruments 51
APPENDIX B
Appendix B Serial Communications
To communicate with the monitor:
• Connect to the serial port using the wiring defined below.
• Set the address of the monitor using the front panel.
• Set the desired communication protocol (ASCII or Modbus RTU) via the
front panel or over the serial interface.
• Determine the register number of the parameter to be read.
• Send the correct command to the monitor and decode the response.
RS485 Wiring
The Liquidew I.S. monitor uses a 2-wire RS485 connection.
Pin Name Liquidew DB9 Pin
A 3
B 2
GND 5
Pin numbers in the manual refer to standard pins on the DB9 D-Sub connector on the rear panel of
the MCU:
Male DB9 Pinout (Liquidew I.S. Monitor on MCU Panel)
1
B A GND
2 3 4 5
6 7 8 9
It will be necessary to match up the A/B (Differential data pair) and GND (0 V) pins with the wiring
of your own third party adaptor.
E.g. For the K3-ADE RS232->RS485 adaptor use the following wiring:
Pin Name Liquidew DB9 Pin K3-ADE DB9 Pin
A 3 8
B 2 3
GND 5 5
This wiring is the generally accepted standard for most 2-wire RS485 equipment.