1734 Digital Input Module Fault status

Hello all,

We had a problem with 1734- Digital input module. The module was damaged because of some short circuit with the Input. We replaced the module and everything works fine. My question, can I get a fault status about the input module. If I have already set an GSV with attribute of fault and still I receive no errors does GSV report only network faults ?The Plc IO didn't receive any fault as well. I think if I have the status if the module fails it is easier to find the problem.

No idea about the electronics in the modules, however, as these are usually isolated from the input circuit the components on the input are unlikely to be monitored for example, if the LED in the opto isolator is damaged by overvoltage then the electronics that put the information on the PLC bus is unlikely to be able to detect it. You will probably find the same problem on outputs. The amount of extra electronics to detect things like this would not be cost effective & what about the greater possibility of faults occurring in the extra electronics.

In general, the GSV only reports on logical objects like the network connection status.

A GSV that reads the 1734 network adapter wouldn't detect a failure of the connection between the adapter and the individual module. And most 1734 discrete Input modules are part of the "rack optimized" I/O connection so there isn't an individual network connection to monitor.

If only the input circuitry side failed, and there isn't any diagnostic features built into that circuit, then there may be no programmatic way to detect that failure.

If the 1734-Ixx module failed entirely, so there was a POINTBus fault, then you can read the SlotStatus word (that's part of the Input connection) to look for the status of each module. It's easy to test that; look at the SlotStatus word and pop an unpowered module out of the POINT wiring base.

Also, when there's a network failure to a POINT adapter, all the Slot Status fault bits = 1, so the overall value of the DINT is "-1". That can substitute for the classic "GSV to read the EntryStatus" to verify a connection to the POINT adapter.