Linking 2 Ge Fanuc PLC's using comms

[balla]

I am trying to link two GE fanuc 90-30 PLC's using RS485 comms one as master and one as slave to enable me two send pulse from master thro link to slave and send pulse back from slave to master. Can anyone help with settings.

[Steve Bailey]

What model PLC? What protocol? Your description of what you want to do isn't exactly the way a master-slave protocol works. In a master-slave setup, all communications are initiated by the master. The slave only responds to requests from the master. What exactly are you trying to accomplish?

[balla]

i AM TRYING TO LINK THE 2 PLC'S AS i HAVE A FIBRE OPTIC LINK STRETCHING 3 KILOMETRES AND BY SENDING PULSE FROM ONE PLC AND SENDING BACK i THEN KNOW THE CABLE IS HEALTHY. i AM USING 485-FIBRE AT EACH END. tHANKS aLEX

[Steve Bailey]

I still don't know what kind of help you're looking for regarding 'settings'. Is this system already up and running and you need to diagnose a problem? Or are you in charge of setting it up? To check the health of the communications link all you have to do is monitor the status word of the COMREQ instruction that controls the serial port traffic in the master's PLC program. If it ever indicates a failure of the slave to respond to a command from the master, you know something is wrong with the communications. You won't know if the problem is in the cable or that the slave PLC has shut down, but at least you'll know when you have a problem.

[RussB]

If all you need is to check that the fiber is still intact, all you need to do is the COMM_REQ to 'Attach'. If this happens without error the connection is good. When setting up the comm_req one of the first parameters is where the 'Status Register' is. 1. Set this to '0' 2. fire the COMM_REQ with a 1-shot 3. verify that the status register has a '1' in it. Anything above 1 is an error. 4. repeat as needed