by cncdrive » Sun Sep 03, 2017 2:56 pm
Hi Rob,
The aux encoders position is read/updated in a 10msec loop and the THC up/down virtual signals and THC speed setting is in the same loop.
You should also take into account that data needs to be transfered to the motion controller which can also take 1msec normally for the ethernet controllers. (data is based on what Microsoft has to say about ethernet latency and in our experience it is mostly true.)
And it has to be processed by the motion controller's CPU which is another 25usec for the ethernet controllers.
So, the best you could get is a bit below 100Hz.
100Hz means that if your Z-axis is moving with infinate acceleration and 1000mm/min feedrate then it still moves about 0.1666mm only per update, I don't think that more latency is really required, but maybe I'm wrong.
The THC control pins on the motion controller are more responsive though, they are in a 4kHz loop in the controller, however I don't think any THC controller electronics are even close to that "fast", because if they are too fast can be a problem to the control loop stability.