dt(s) value on Plant Simulator

[martinby]

Hi, I am doing a simulation project that involves a PID block and a Plant Simulator. From observation, varying  the dt(s) value on the Plant Simulator makes a big difference to the output.I expected the dt(s) value to the PID block to have a bigger impact. Is there a reason for this? Thanks,Martin  

[adlb]

Hi Martinby,

Could you give us a little background on what you are looking to do and a screenshot or demo vi for what you mean?

Regards,

Andrew

[nathand]

How much effect the dt value has on the PID output will depend on the PID gains - for example, if you have a pure proportional controller, the dt will have no effect at all, and if your integral and derivative gains are small then dt will have little effect. The dt should be the same for both the PID and the simulator (the time, not necessarily the value - they could use different units). In a real system you should generally leave the PID dt unwired, so that it will use the real time difference between executions.

[martinby]

Thats great, thanks a mil for that,Martin.