How to Choose control loop time?

How to Choose control loop time?
Need to consider the contents including what?
I think the encoder change must be consider, because if in the loop time the position not changes, the pid may be out a bad Value。

In addition to the encoder, what else contents to consider ?

Here are some considerations:

  • In general, a shorter loop time provides better control.
  • At lower loop times, the number of axes is decreased. This is described in the RMCTools help, in the Loop Time topic.
  • Magnetostrictive sensors may require a minimum amount of time to obtain a reading, based on the length of the sensor. If such sensors are used, the loop time should be set to be greater than that time.
  • If the user programs include steps with a lot of calculations, the RMC may require a longer loop time. You will probably not have to worry about this since it is very rare to have so many calculations.

I don’t think that it depends so much on the encoder. Make sure the encoder has reasonable high resolution, and the control should be fine.

thank you for your reply.

about red part :
the Incremental encoder don’t care the time? its refresh speed is very fast compared with rmc150 loop time ?

The incremental encoder is not affected by the loop time. It always sends signals to the RMC based on its own motion. Yes, its update rate is much faster than the RMC loop time.