PLC5 PID Config Lock

I am working with a PLC5/40C and am having some problems with the configuariton of one of the PID loops.
The max output paramater was originally set at 100% but has changed to 81%. I attempted to reset the value to 100, but when I weent back in the new avaluew was not displayed. Is there a lock that could be in effect? Also, can you make changes to PID on-Line?

Jack

Check to see if something in the program or HMI/SCADA is writing to that parameter.

Post your .RSP file ( zip it first ) and someone can help you look. Tell us which PID if you have more then one.

jfuehring said:

I am working with a PLC5/40C and am having some problems with the configuariton of one of the PID loops.
The max output paramater was originally set at 100% but has changed to 81%. I attempted to reset the value to 100, but when I weent back in the new avaluew was not displayed. Is there a lock that could be in effect? Also, can you make changes to PID on-Line?

Jack

Click to expand...

Welcome to the Forum!

There is no lock for the PLC5 PID that I am aware of. Yes, you can make changes to the PID Online, but be very careful. Putting an invalid Value in can Fault the PLC.

Is it possible the Value is being overwritten in the PLC Program somewhere or by an HMI?

For more information on the PLC5 PID Instruction, have a look at Chapter 14 of this Manual.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1785-rm001_-en-p.pdf

Stu....

Good Call. This PID controls an inlet pressure to an environmental system. If th outlet pressure gets too high, it clamps the inlet hi limit.
Thanks for the advice.

jack