Allen-Bradley PLC 5/20E 1771-OW16 Problem Please Help!

I have added a relay output module 1771-OW16/B to slot 5 of my 1771-A4B chassis that has a 5/20E host processor. I have added the 1771-OW16 to the hardware configuration and programmed 12 of the relay outputs I need to trigger various radio alarms and downloaded the program changes. When online I can force the relay card outputs and they come on however, in my online program status they should be on already for the various true alarm conditions but the outputs never show true, can anyone help?

did you reference the outputs in more than one line of logic?

Is your new logic in a subroutine that's not being called?
You need a JSR instruction in ladder 2 that calls the sub.

Are the new rung of logic in a new "Program File" is so did you remember your "JSR" rung on your main Program File (Usually LAD 2).

That would allow you to force outputs but your code would appear not to work. "Been there, Done that".

Sounds like an unscanned program to me as well. In addition to the JSR option for calling a subroutine, you can also visit the processor status area and add the number of the unscanned program to the list, which will cause it to be scanned just like the usual Ladder 2 routine. You can have up to 16 of these entries.

Best Regards,

Bob A.

Thank You Keystone! That is exactly what I did, I created a new program file and did not remember my "JSR" rung in my main program file. I thank you again for the help!

One other possibility that could be causing your unscanned rungs is the MCR function. A Master Control Reset appears in two parts, the first is conditioned by some logic that determines when to enable and when to disable the rungs that follow it. This portion of the program is concluded with a second unconditioned MCR which is the "end" statement.

When the first MCR is False, everything that follows down to the second MCR is held Reset (OFF). This is similar to a jump, but includes the "Force Off" functionality as well.

When the First one goes True, the following rungs get scanned in normal fashion.

This function is similar to a subroutine, but does not carry the added overhead time to do the jump to the second program routine.

Bob A