PID is oscillating

[catchvsystems@sify.com]

Hi All ,

I am using PID vi from labview.My output and process value is oscillating between max output range and minimum out put range for a long time.What is the mistake ?

I am new to labview. I am using propotion control value as output control.Pressure transmitter as my process parameter.

[jyang72211]

If proportion control value (K_c) is increased further, the oscillations will become larger and the system will become unstable and may even oscillate out of control.  See link below for more information.  

https://www.ni.com/en/shop/labview/pid-theory-explained.html

[jyang72211]

If you look at the article, you will see that you need to 

1. Adjust the proportional term to get fast response, but you will get oscillation at steady state.

2. Adjust the intergral term to get close to zero steady state error (getting rid of oscillation), but you will get overshoot.

3. Adjust the derivative term to lower overshoot.