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Intellisys Modbus RTU COM Port to DB9 CM 1241 (RS485)
2 Wires RS485 to DB9 in Modbus RTU Protocol.

Dear All

Sorry for my English

I have Siemens CM1241 and need to communicate with Intellisys XE 90 via Modbus RTU, period.

The problem is, from XE 90 the connector is Phoenix Contact 2-Position Screw Plug Connectors MC 1,5/ 2-ST-3,81 1803578, or in other word, only 2 contacts form P9 COM1 = L1 , L2.

How we connect it to DB9 Female in CM1241? What signal go to what Pin? How about the Ground? Do I need Resistor?

Thanks for all your supports

Best Regards

Solution on Siemens forum: