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newbieplc2003

Move Function Not Working

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I am very new to PLC's, I work in a power plant and we have an ABB DCS. We have some vendors that use PLC's and they try to make them work with our system. Currently I am working on a project were I am trying to add 8 analog outputs to the PLC. I am working with two 1756-L71 controllers (redundant) and the rev for the program that was written 20.01. Basically I have 8 analog inputs that I want to bring to the spare analog outputs that I have. I want to see these inputs in our DCS. I wrote simple logic that at the end of the rung has a move block moving the source which is the input and taking it to the destination which I made an alias tag for the output channel that would correspond. Problem is I can see the source number moving, but the destination number stays at 0. I can type a number into the destination and it will work. I can see my 4-20 signal I am sending out in the DCS. Everything before the move function is true, I have and open contact, and a closed contact and they both are green. This is happening on all eight of my outputs that I am working on. Please help I have learned a lot from this experience but I cannot figure out what has me stuck this time.

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are the rungs you added scanned? is there anything else writing to those outputs?

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I agree; be sure that the Routine you have that logic in is being executed. Only the "Main Routine" in each Program is executed automatically; all the others have to be called with JSR instructions. It can be a little confusing because you can still view the logic and monitor data values online, including the preconditions on the rung.

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I agree - you're not scanning/executing the new rungs ... if you've just added a new Routine to your existing project, then a JSR (Jump to Subroutine) should get you going ... on the other hand ... if you've made a new program for this project, then the link below might help ... http://www.plctalk.net/qanda/showthread.php?p=567395&postcount=9

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