S7-1200 PID issue

I'm using a S7-1200 1214 CPU with version 10.5 TIA software to control a chilled water loop- but even with compact PID instruction enabled and everything working the analog output has no effect in auto. If I put the PID DB in manual it operates the modulating valve (4-20mA output) fine. In the PID loop tuning screen the output seems to operate OK too, and there are no fault codes- anyone have ideas on possible issues? I'm about ready to yank the processor and put in something else.

Hi and welcome to the forum.


I never tried a 1200 PID, but could it be you need to invert the controller / use negative gain?

Kalle

Its a chiller loop, so in this case the PID output is inverted. The PID monitor shows its trying what I want it to do....

TIA10.5 PID was a pain in the backside. You seemed to have to go through the auto tune system and then enable the loop before it worked. TIA has no gone through V11 and is up to V12, so an upgrade my be a good idea.
Otherwise have a look here:
https://www.automation.siemens.com/...ng&ForumID=265&Language=en&onlyInternet=False
It is the Siemens official forum, you will find lots of stuff on the old PID. If you upgrade to T11 or better you could look at various alternative PID loops available on the site. You will also find a lot of people complaining the we have turned in to the TIA Beta testers.