![]() ![]() ![]() The time that you have paused will have a more significant impact on the integral term. The effect of a large accumulated time between calls will be to reduce the response of this term. The derivative output will kick in when there is a change in the process variable (use of the process variable prevents derivative kick). If you have "paused" calculation for some time, this will have an impact on the integral and derivative output. Since you have not specified a dt, the PID algorithm uses the accumulated time between calls. In the VI itself, dt will be either 1) what you set it to, or 2) an accumulation of time based on a tick count stored in the VI (the default). If you take a closer look at the PID VI, you can see what is happening and why you might not get the response you expect. Also, the PID VIs are coded in G so you can simply open them to see how they operate. ![]() A great reference for understanding PIDs and how they are implemented in LabVIEW can be found here (not sure why it is archived). What Yair said is not entirely true - the integral and derivative terms are indeed time dependent, but the proportional is not. ![]()
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