Closed Loop stepper

If the drive and motor get out of sync by a few steps, the drive will stop the motor and issue an alarm signal which can be fed back to the pc to stop the gcode program running.

It is a good idea to connect this alarm signal because there is no interaction between the drives to stop the other axes at the same time if one axis has an error.

The drives will, as already said work with any system (Linuxcnc, Mach, Grbl etc) that has step/dir outputs.

Hi..just saw this...from tommylight.."LinuxCNC has real time control, mach3 on widnows does not "
So with what you said does that mean I do not need ess..and that drive does the compensation real time separate from linuxcnc? if so does that mean it will also work real time in mach3?
Thanks again for your help!..I am thinking of switching over real soon so I just want to make sure of what hardware I need

Realtime has nothing to do with these drives or motors, it comes from whatever is controlling them, whether it is a pc parallel port machine such as with Linuxcnc or from a custom controller connected to a pc by usb or whatever.

I haven't used Windows or Mach3 for many years. When I did it worked fine as a parallel port controller, but there is a reason why it now seems to have been rewritten to use an external controller.

It will drive these steppers ok, but if the parallel port pulse timing starts to go adrift, these drives will not correct that problem, they will lose position.

so from what I have read...which is itself a potential problem in that it may not be accurate...The difference between mach3 and linuxcnc as it relates to the driver/motor I have is that mach3 will make a correction of lost position at the end of the movement..whereas linuxcnc is capable of making the correction real time..
The reason that is important to me is that if one motor of the 2 i have running my x axis stalls a little..I will be out of square..I am running a saw blade to rip lumber..any slight change in angle messus everything up..that is why I cant wait till end of cut..

Things are a bit mixed up here. With these drives the pc sends pulses to the motor drive either directly (parallel port) or through a plug in board and there is no feedback from the motor position to the pc at all, it is an open loop system. If the motors are not where they should be, there is no compensation made by the pc, and the motors will remain out of sync with the commanded position.

The feedback is between the motor drive and the encoder on the motor, so if the motor does lose position compared to where the drive thinks it should be, the drive will compensate and try and move the motor to the correct position.

Interesting parallel between technology and communication..As I said before ..I am trying to understand everything that has been said..
So then it does not matter about controller(pc)...it is the drive ...so what I have should work on mach 3 making realtime compensations when encoder says so..is that right?..I appreciate your patience!!