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Connecting 2-wire modbus RS-485 to 3-wire Modbus RS-485

A

Thread Starter

ASh

I used ADAM-4051 which is 2 wire modbus (Data+ and Data-) and Eurotherm 3508 which is 3 wire (Data+,Data- and Gnd), and a MOXA 3180 convertor which convert Modbus RTU to Modbus TCP? how can i connect these equipments in a one modbus loop?
 
E

Elmer Bulman

Start with the MOXA 3180 and add one slave at a time. Do not be suprised if the Data+ and Data- wiring needs to be reversed on one or more devices. Ideally a Data+ is wired to a Data+ and a Data- is wired to a Data-. All common/ground wires are connected together. If a device does not have a the GND connection then try using the DC- connection OR leave it float (not the best choice). There can be only 2 ends to the RS485 data highway with a 120R termination resistor at each end. It does not matter which of the 3 devices are at the end of the highway.
 
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