I/O Module fault in AB's PLC

Dear All,

How can I get the I/O Module fault in AB's PLC?
I have already studied the HELP, but still cannot get that fault bit. Can anyone explain in detail? Thanks

Allen-Bradley makes several different programmable controller families; you should specify which controller you are working with, and which type of module.

Do you need to detect a total module failure (like removal of the module) or are you attempting to detect one of the diagnostic features of the module, like short-circuit or open-circuit detection ?

Is the module in a chassis with the programmable controller, or is it in a remote chassis on a network ?

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I/O Module Fault

Dear All,

The Processor is 1756-L61, and there is 3 Remote I/O chassis connected with ControlNet Module. One of the Module is DH+. The other are IB32, IV32, OW16I, IF6, AF4. If either one of the module has fault or disconnected, there should be a alarm bit in the program.
How can I get this alarm bit ?

Thanks

Look up the GSV instruction and the "EntryStatus" object; in RSLogix 5000 Help the best keyword is "GSV/SSV Objects". My standard method is to divide the EntryStatus target tab by 4095 to bring the significant bits to the right by 12 bits, and compare the resulting value to constants. 4= good connection.

If you have a Rack Optimized connection to the remote chassis, you can use the SlotStatusBits word to check on the overall network connection, because all the bits will = 1 when there is a lost ControlNet connection to the chassis. That will make the SlotStatusBits tag value = -1.

An additional way would be to get the status of the I/O LED light on the front of the controller. This would be obtained via the GSV instruction.


There are several ways to accomplish what you are discussing. Depending on your requirements, the solution could be different.

RA Tech Website would be the first place to visit.