Connecting I/O cards between two PLCs


Thread Starter


I have two separate PLC. Both are having the I/O cards of 230 VAC. I have to give one signal from one PLC to other. I have taken a Digital output from PLC and given to Digital input card of other PLC. Please suggest what wiring I have to do? How the phase and neutral wiring will be done? Can I use the phase of first PLC card and the neutral of other PLC Card or I have to take the Phase and neutral of first PLC only?

Dinesh Chauhan

You Should use 230 VAC relay instead...
DO of 2nd PLC will operate a relay whose contacts are acting as a DI of the 1st PLC and visa versa...
In theory the neutrals should be at the same potential, especially if both PLCs get their supply from the same transformer or they share the same common grounding point.

I would run a cable from the outputs across to the inputs of the other, include a neutral but don't connect it that way if you need to add interposing relays or transformers you are prepared.