PID Configuration Logix 5000

Hi,

Im hoping somebody can help me out with trying to configure a PID controller on a project I'm currently working on.

I have never configured one before and have been reading through the many informative posts on here in my quest to get it working.

Basically I am using a vacuum sensor to control the main electro pneumatic vacuum regulator. For the process which is a test rig, I require a constant vacuum of -5.2kpa during the test process. I am trying to use the analogue output of the vacuum sensor to feed into the PID Instruction and control the analogue input into the vacuum regulator. However I been struggling for over a day on this now and seem to be getting no where.

The relevant parameters are:

Vac regulator (Analogue Input 0-10VDC), scaled for PID units (0-16383)

Vac Sensor (Analogue Output 1-5VDC), scaled for PID units 0-16383) engineering units = Max 0, Min -101.3)

I would be grateful if anyone could point me in the right direction regarding how to configure it correctly. I have attached a zip of the L5K file. The PID is in the Task Fluid Control, program Fluid control with the PV being Local:3:I.Ch3Data and the CV being RegulatorControl_Activac.

Thanks in advance

Mister Mac said:

Vac regulator (Analogue Input 0-10VDC), scaled for PID units (0-16383)

Vac Sensor (Analogue Output 1-5VDC), scaled for PID units 0-16383) Local:3:I.Ch3Data and the CV being RegulatorControl_Activac.

Thanks in advance

Click to expand...

scaling for 0-10dc 0 to 32767 -+10vdc

Hi Pino,

I dont fully understand your reply. In the properties of the Analogue output card, if the option of "Scaled for PID" is selected it gives the Min/Max values as 0-16383

What do you mean when you say that you are "getting nowhere"?

Have you attempted to control the process in manual mode? If so, what happened?

What happens when you try automatic mode?


BTW: You've probably already seen a link to controlguru. It contains a wealth of useful information.

Hi Bit Bucket,

What I mean is that when I run the system my PV makes no attempt to go to Set-point. The output is at 100% and there is a large error value present but the PID does not seem to function correctly.
As I said I have never worked with PID before so am a novice in relation to setting one up or troubleshooting. Thanks for the link, it does indeed have a lot of good info.

maybe it's just my system - but when I convert your L5K file to ACD and open it, I get about 4 errors - including the "undefined tag" error shown below ... so I can't get into the PID to see how you've got it set up ...

suggestion:

try VERIFY CONTROLLER - make sure there are no ERRORS - and then post the file again ...

.

watch this
http://www.youtube.com/watch?v=TpmOJ9gKaZw

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1746-um005_-en-p.pdf

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1756-rm003_-en-p.pdf

Hi Ron,

Have re-posted the file and removed the cause of the errors. There are a couple of warnings but nothing that should cause any issues

I'm teaching this week so it will be late tonight before I get a chance to look at it – but WHERE did you post the file? ... it needs to be attached to this thread – the same way that you did the first version ...

hopefully someone else will be able to nail it down for you before I get back around to it – but I'll try to help when I get a chance ...

Apologies forgot to attach file


Thanks for all your help