PID autotuning not working

[Dani81]

Hi all!

I'm trying to use the pid autotuning vi, but I have some problems.

Everithing works fine for the first two steps (setting type of control, realy amplitude and calculating noise), but the program seems to stop when it has to calculate the results.

The input switches between set point+relay and set point-relay just once: when there is the transition between the two levels the output keeps fixed at 0, even if when it should increase to follow the set point.

The program keeps running and the graph keeps updatuing, but there aren't the required oscillations.

Could someone help me?

Thanks!

Daniele

[Hudson]

Hi Daniele,

Its hard to understand and explain why your PID Autotuning VI stops. I can image three possible reasons:

1. Your VI main stops execution while the PID Autotuning VI is running. Check thus the execution of the two applications.
2. You should provide proper parameters to the PID Autotuning VI: Before you begin auto tuning you must establish a stable system even if you cannot tune the system on your own.
3. Your PID Autotuning VI is corrupted - try to run a simpler code or example VI to verify its functionality. In case repair your toolkit installation.

Hopes this helps

HUDSON

[Hudson]

I forgot to say that another possible reason is that you are tring to use the PID Autotuning VI under a RT OS.

HUDSON