PLC 5/30 Remote I/o communication

I am replacing PLC 5/15 cpu with the PLC 5/30 cpu. It is not communicating with the Remote I/O with the second rack. I think it should connect with the same DH+ connector to communicate with the remote I/O but it is not communicating. Is there any other setting or any dip switches to be changed.

Data Highway Plus and Remote I/O are different protocols that run on identical wiring.

On the PLC-5/15, the 3-pin port marked "Peer Comm Interface" is DH+, and is wired in parallel with the 9-pin port.

On the PLC-5/15 the lower 3-pin port marked "Rem I/O" is the Remote I/O scanner.

The PLC-5/30 is similar; it has one port for DH+ (Channel 1A) that is connected in parallel with an 8-pin Mini-DIN port, and one port for Remote I/O below it.

Be sure you are connecting the correct ports and using the terminating resistors correctly as well.

You can try switching the blue and clear insulated wires; while there is a correct way to do it (Conductor 1 to Conductor 2) many installers make mistakes.

Post your program if you can ( zip it first).

thanx Mr ken we just switched the wires from connector and yes it is now communicating