Why doesn't the output energized when toggled?

novice · Nov 6, 2008

The problems just keep coming. WHy doesn't this program behave like it should?

I have three controllers with identical programs. Yet the other two are working fine but this one isn't.

jtn · Nov 6, 2008

Is that routine being called to run?
Is the address have another OTE or OTU somewhere else in the program?

novice · Nov 6, 2008

Yes to the first question. No to the second.

I have two identical programs. Yet in those two, the output does energize when input is toggled. But in this program, it doesn't. Not unless the output itself is toggled.

Critt · Nov 6, 2008

Is the processor in run mode?

Lancie1 · Nov 6, 2008

Only guesses are possible from this remote location.

1. The 3 programs are not exactly identical..There is a relay somewhere that is de-energizing XI_7689, or

2. These rungs are inside a sub-toutine, or

3. The PLC is not running, and this was its last state before quitting.

How come you used XI_7689_DCS to seal in XI_7689? Seems like it would be best to use XI_7689 to seal itself.

KP_EENG · Nov 7, 2008

If the code is in a sub-routine, make sure that you are calling the sub-routine. If it is not scanned the output will not energize. Also, make sure that you have not somehow duplicated the output elsewhere in the program. It could be turned on then off in the same processor scan.

Regards

Ken M · Nov 7, 2008

WHy doesn't this program behave like it should?

All programs behave like they should. Perhaps not as we expect, but always like they should.

I'm sorry. For some reason on this PC I can't view the image you've embedded/attached so I'm reduced to just making smart unhelpful remarks. (Hmmm... no change there, mutters the rest of the forum ...)

Norml · Nov 7, 2008

novice said:
The problems just keep coming. WHy doesn't this program behave like it should?

I have three controllers with identical programs. Yet the other two are working fine but this one isn't.

Your image has garbage and pop-ups attached to it.

Sergei Troizky · Nov 7, 2008

Clarify the question, please.
I do not see any toggling logics in the code fragment, assuming that "toggle" means bidirectional changing the bit state to opposite.
Do you probably mean your attempts to toggle the bit manually from online PC?

Krilun · Nov 7, 2008

I've had this EXACT problem before too. What I do is delete the element and then insert a new element of the same type. Try that, sounds childish but it fixed my problem.

novice · Nov 7, 2008

To answer all your questions:
- it happens during Program Run
- how do I know if the sub-routine is being run (or not)?
- XI_7689_DCS should not affect the output because the Modbus relay is opened
- the output isn't duplicated elsewhere; I've checked using cross-reference search

I ended up using one of the other identical program, do "Save As" and correct the tags. Took care of most of the problem.

To Krilun,

Do you have to delete and re-create the same tag as well?

Krilun · Nov 7, 2008

I didn't have to delete the tag itself, but if deleting the element and replacing it doesn't fix it try recreating the tag that is having the issue.

also you may want to cross reference that tag to make sure its not getting two conflicting values.

jshiepe · Nov 7, 2008

Is this PLC attached to an HMI that could possibly have control of the bit in question? The PLC and the HMI could be fighting over control of the same bit.

Jeff

tomalbright · Nov 7, 2008

You say the output is not cross referenced... try cross referencing the ALIAS, or output, to see if you have mistakenly assigned the alias to more than one tag.

Good ol' RSL5000... I love it, but whew.

geoplc · Nov 7, 2008

This can happen if you use the same OTE instruction in multiple places in the program. If you need to have the same output in several different rungs or ladders, even if the ladder is inactive, you need to use it as an OTL and OTU.

Why doesn't the output energized when toggled?

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