what are the parameters that needs to be taken into consideration while deciding the cycle time of a PID controller for a given process?

 

If the cycle time is too long, then the lag in the feedback might make the loop unstable. If the cycle time is very short, there is usually no problem, unless you are using the "D" term in the PID. In that case having a cycle time that is too short could make the "D" term be essentially just noise. This can be fixed by forcing a longer time span for the "D" term calculations.

Robert Scott
Real-Time Specialties
Embedded Systems Consulting

 

A time signal can transformed to frequency space. The spectrum of this signal will be limited in bandwidth. According to sampling theory a signal that is limited in bandwith must be sampled at least twice the period of the highest frequency in order get it correctly.

Instead of using a simple PID controller, I would suggest a PID-T1 controller in order to eliminate noise.