Modbus Cable Length

[M.J.Saleh 1]

Hi I am using a Modicon PLC and tried to connect Siemens TP270 Display via Modbus interface to That PLC , But now Please tell me how much is the Standard Cable Length For Modbus Interface ? and which Convertor Modulle i must use to chang My Bus from Modbus to Modbus+ in order to increase the cable Length ? Thank you so much

[Crossbow 294]

The only way to get Modbus devices on Modbus Plus is with a Modicon Bridge Plus. That Bridge Plus connects Modbus serial devices to Modbus Plus network. It's not a cheap connection either, as Modbus Plus is a proprietary high speed bus (similar to AB with DH485). You're probably best leaving the interface on RS232 which typically can't be more than 15 meters.

[redfred1 0]

You can always go to an RS232 to RS485 convertor to get more distance...1200 meters/4000 ft.

[Crossbow 294]

Depending on the PLC, there might be an RS485 Modbus option module available. That would be a good bet.