Remote I/O Link Loss...

I have a PLC5 (local chassis), and there is a remote I/O connection to some Flex I/O inputs (via 1794-ASB). Some of the inputs on the Flex rack control outputs on the local chassis. Question is "If I want to de-energize (or prevent energizing of) the outputs on the local rack that are controlled by the remote rack, in the event of a communication failure, what bit can I use in the code to keep a check on the remote I/O link integrity"? Hope that makes sense. Thanks!!

One simple way would be to set up a heartbeat with a spare output and input on your remote rack. Send a signal to the output that is connected directly to an input, if you lose the input signal then a comm loss has occurred.

Thanks Mark...I've done this sort of thing before. I was wondering if AB had a built-in bit for this purpose.

bluenoser337 said:

Thanks Mark...I've done this sort of thing before. I was wondering if AB had a built-in bit for this purpose.

Click to expand...

Yes, there are rack fault bits for that rack, but if an individual card within the Flex I/O rack fails, whether or not a rack fault is generated may be determined by dip switch settings on the 1794-ASB. Since Flex I/O supports R.I.U.P. it is optional whether or not to generate a rack fault.

Also, the functions of some of those dips witches had different meanings with older ASB's so tell us the revision level of the ASB for more info.

For the main adapter faults, you should be able to locate the relevant bits by perusing the processor status file.