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RS485 Communication Wiring Diagram for a Momentum Processor to a Merlin Gerin Digipact DC150

Goals and Symptoms

The purpose of this resolution is to diagram the RS485 wiring for Modbus communications between a Momentum processor and a Merlin Gerin DC150. The RS485 pinout shown in the DC150 User Manual is incorrect.

Facts and Changes

All Momentum Processors can be used in this application. The following have a builtin Modbus RS485 communications port and do not require a 172JNN21032:
· 171CCC98020
· 171CCC98030
· 171CCS78000
· 171CCC78010

  • The following Momentum Processors do not have a builtin Modbus RS485 port and requires a 172JNN21032 Option Adapter to work in this application:
· 171CCS70000
· 171CCS70010
· 171CCS76000
· 171CCC76010
· 171CCC96020
· 171CCC96030

  • The Data Concentrator is:
· Merlin Gerin Digipact DC150

Causes and Fixes

RS485 wiring from a Momentum processor (port 2, db9) to a Merlin Gerin DC150.

NOTE: The signal pinouts for the db9 RS485 connector as shown in the Merlin Gerin DC150 User Manual are incorrect. The correct pinouts are shown above.
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  • RS485 wiring from a Momentum 172JNN21032 Option adapter (port 2, RJ45) to a Merlin Gerin DC150.

NOTE: The signal pinouts for the db9 RS485 connector as shown in the Merlin Gerin DC150 User Manual are incorrect. The correct pinouts are shown above.


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