Hi All, can anbody explain why in PLC or DCS analog input modules the output rate is often many times the step responce. eg one +/-10V input module had an output update time of 10mS but a step responce time of100mS. Similarly I have seen modules with a 3dB point set to 17Hz and the output rate at 1Khz.
Is it something to do with PID control requirements?
These are analog input modules so output rate is the conversion rate of the analog to digital conversion signal sent to the controller.