Microbictomb

SLC 5/04 Output Issues

6 posts in this topic

Hello everyone, I'm hoping someone can help point me in the right direction here.

I have a 13 slot chassis with a SLC 5/04, 4 IB-16 modules, a DeviceNet Scanner and then 4 OB-16 modules in that order.

My issue is after completing my ladder logic with timers to control multiple outputs I was only getting one output to turn on.  I noticed while watching the ladder in Run mode that all my input conditions were on and working as intended but the output would not energize even monitoring the ladder.  The controls I needed/used were all on slot 6 output.  My output in slot 8 had all my LED's on it.  So to test I disabled all rungs in my ladder and left one timer on with a push button input condition to turn on T4:0.  With T4:0/EN NO to O:8/10 (green stack light).  T4:0/TT NO to O:8/11 (yellow stack light).  T4:0/DN NO to O:8/12 (red stack light).

Green light works, yellow and red do not turn on even though the input condition is good.  They do however turn on if forced on.  That's where I'm getting confused.  I swapped output modules with no results.  I moved all 3 lights to branches with just the T4:0/EN condition and the same results.  I moved yellow to output 15 and it works.  I moved the terminal block/wires to slot 9 and changed the ladder to match the new slot and they all work.

 

If my backplane is bad and the problem, why then do the outputs work when forced on?  Is it possible it's the processor instead that's the issue?

Edited by Microbictomb

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Can you post the code file?

 

Make sure the output is only ever used in one location of your program.

Edited by adohm

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It would be easier to help if we could see the ladder logic

Although your test method should work try using a button

And last, are you sure that you aren’t trying to control an output from more than one rung. Ie one rung turns it on but somewhere else it’s being turned off. It happens more often than you would think. Some of us have even made that mistake more than once. It’s really fun when you do it in big program that uses multiple languages. :)

Troubleshooting is half the fun

i never say that when I’m troubleshooting 

 

 

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I actually wrote 3 rungs additionally at the end to control my original outputs with push buttons and they worked which is what led me to think it's in my logic/timers.  But I disabled every other rung in the program with an input that's not used.    I'm going to write a new program with just the one timer and the lights to see if that works, if not I'll post what I have.   I don't have internet access on my programming laptop so it'll take a bit to find a flash drive and transfer the file. 

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The fact that your outputs work with push buttons at the end of your program points even more to the issue that Michael referred to - multiple outputs with same address.  It does still sound as if your original outputs were being overwritten somewhere before the end of your program.  Why dont you do a quick cross reference of the addresses and see what comes up?

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It was in my logic, I wrote just the timer and the outputs and they all worked.   It's been a couple years since I've done a semi-complex program so just a little rusty it seems.   Thanks for the quick replies everyone

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