Southpark:
sampling at some relatively fast rate where system performance doesn't get much better than some minimal optimum rate is probably just waste of resources and time etc.
With all due respect, I was not asking (in Reply #6) what sampling rate should be used.
Am I correct to think you are saying two separate things here.
{A} there is no value in updating the PID calcs more often than new input data are collected
{B} the PID calcs should not be done at more often than half the update rate of the sensor
I'm not sure I understand the second one. Do you mean that if I sample a temperature every 6 seconds I should only update the PID calcs every 12 seconds?
And (a separate but related question) if the heating rate is such that the temperature will never increase by 1°C in less than 6 seconds are you saying that I should test the temperature every 3 seconds and call the PID function every 6 seconds? (Of course I am assuming that 1°C steps are sufficient)
Thanks
...R