PLC/PID random issues

Hello,

what in programming could cause a random change in how a PLC-driven piece of equipment operates for the worse, after hours of operating.

Power cycling resolves issue though, temporarily.

Juice1030,
You might have to be just a little more specific.

You could start by telling the forum what PLC you have.

operates for the worse, after hours of operating.

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Can you expand on the above statement?

Power cycling resolves issue though, temporarily

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Is the PLC faulting, and cycling power clears the fault?

Well, the piece of equipment (w/ Allen Bradly PLC) starts the beginning of the day working normal. After 1,2,3,4 or 5 hours, etc., never consistently is it at a specific hour, the machines performance declines dramatically and is inconsistent in performance. After rooting high and low mechanically, we are opening up to the idea that it may be faulty in the programming or computer/controller related??? The reason we determine that is because by turning off the entire machine, waiting 5-10 minutes, and turning it back on, the machine starts operating normal and fine again. If again the performance begins to decline, we turn off/on the power again and resume like nothing happened.

We do not have a programmer in-house, so we rely on the manufacturer of the equipment of who which is useless to us. The machine does not allow us (the user) to see faults from the PLC or any of the controllers within the entire system. We are limited in that regard.

It is certainly possible, but we really have no way of knowing without seeing the program. If you could be more specific with what the machine is supposed to do, and exactly what it slowly does less well, we might be able to make at least an educated guess.

My Crystal Ball is not working.

Maybe you should call someone with knowledge of your PLC (with software) and your machine.

Do you have a Magic 8-Ball? May have a clearer answer with that.

But seriously, contacting a programmer will be the next step. Just wanted to possibly get some insight from knowledgeable forum heads.

Juice1030 said:

Do you have a Magic 8-Ball? May have a clearer answer with that.

But seriously, contacting a programmer will be the next step. Just wanted to possibly get some insight from knowledgeable forum heads.

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Lots here would be more then glad to help.

Allen Bradley makes several different PLC's ( PLC5, SLC500 series, Micrologix series. CompactLogix series. ControlLogix and a few oldrer ones.

performance declines

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????

Help someone help you. That's why we come here, look below.

Juice, you need to be VERY specific and detailed in your problem description.
General questions generally irritate people on here because there are a 100 reasons you could be having issues. Without very detailed hardware and problem description it is pointless to give you suggestions because it can be anything.

It is the A-B CompactLogix L32E

Something physically on the machine is cooling down/getting more viscous/developing more or less friction while you are stopped and that is what is causing your change in performance. If it was purely software related a 10 second power cycle would do the same thing at a 10 minute power cycle. the fact that you have to keep it off that long is an indicator that something physical is changing.

Keith

+1 kamenges.

I get this all the time at work... "Check the program, xyz isn't working like it did last week".

99.9% of the time, something is broken on the machine, be it a bad wire, broken bolt, sheared shaft, no oil in the pneumatic oilers, low fluid... you get the picture.

PLC programs as a general rule do not just 'drift', any more than computer programs do something different every time you start them.

Of the remaining 0.1% of the time, .075% is because an edit was made to the PLC program in a hurry without investigating side-effects. The other 0.025% of the time, there is an actual failure on the PLC, but that is almost always a bad I/O module or point.