GE PID Problem - GE - PLC Mentor

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2/26/2009 10:12 PM

	PLCprogrammer
5 posts

GE PID Problem

I have a GE 90-30 CPU 374 PLUS. The program currently has a PID controller that controls a valve. I would like to add a second PID controller to control fans. However I am having a problem implementing the 2nd PID controller. When I upload the program and run it, all the parameters are constantly changing. The P,I and D gains fluctuate, upper/lower clamps, etc are changing. The original controller still functions properly. Moreover, if I remove the old controller (mixing valve) and run it, the new fan controller now runs fine. I ensured that the controllers each have enough reserved memory (40 words). Has anyone had any similar problem?

2/27/2009 7:39 AM

	AutomationNC
72 posts

Re: GE PID Problem

Sounds like something is being overwritten. Are you sure the new PID addresses are not used elswhere? Have you done an implicit search?

3/2/2009 3:53 PM

	Zackbo
26 posts

Re: GE PID Problem

Are you using Proficy ME to program? The 374's are known to be a little flaky, even though they are the highest-end CPU you can get for a 90-30 platform. Are you using PID in ladder, or in a FBD?

3/2/2009 4:12 PM

	PLCprogrammer
5 posts

Re: GE PID Problem

turns out i did have something that was overwriting the PID registers

4/2/2011 7:45 PM

	donnie
4 posts

Re: GE PID Problem

I am a newbie at setting up a PID loop. I am getting 2 errors and cannot download. 8141 unexpected instruction. 8149 missing power flow.

I need some type of sample to get this project test going. I am using a versamax micro / nano IC200UAL006. My GEXPRO support has been out of town all week and I turning to the PLC forum. Anyone?

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