PIC Controller on GE 90-30

Hi,

I have a GE 90-30 CPU 374 PLUS. The program currently has a PID controller that controls a mixing 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 problems? I couldn't find any documentation that stated the 90-30's could only handle 1 PID controller.
Any help would be appreciated.

Hi,

are you sure the new PID addresses are not used elswhere? Have you done an implicit search?

For the start of the new PID, try assigning it to start at %R which will automatically give you the next free address.

Cheers

Thanks for the reply. it appears the address was used elsewhere after the implicit search. I will try the program again and update this thread.