I purchased the Pololu Jrk 21v3 USB Motor Controller with Feedback, 8-28V 5A. It is really an excellent DC controller.
I am controlling the speed controller with the following CNC controller, but I want to be able to stop and start the small DC motor (to be used as spindle in my project).
We are not very familiar with those CNC controllers, and it is not clear how they relate to using the Jrk in your setup. Can you clarify what you are trying to do, and what part you are having trouble with? Do you have questions that are specific to the Jrk controller?
As I said in my previous post, we are not very familiar with those CNC controllers, so it is not clear to me how you are using all of those controllers together.
In general, the Jrk supports multiple interfaces for controlling a motor; however, if you are using a separate microcontroller as your main controller, it is probably most practical to use the Jrk’s TTL serial interface. You can find more information about the supported protocols and motor commands in the “Command Protocols” and “Motor Control Commands” sections of the Jrk user’s guide, respectively.