Enable pins on Stepper driver, are they required?

[magicniner]

On the actual function of enable pins, a useful way to use them is to position work on the machine, jog the tool to your desired reference point, hit the disable switch and jog the controller to the matching position on the path display without moving the steppers. You could manually position the machine while the steppers are off if it has handwheels,

- Nick

[Robin Hewitt]

There is a big difference between PAUSE and emergency STOP. If everything goes to hell in a handbasket I usually retreat to the safety of the mains socket and kill the power there. This does preclude braking the spindle at the VFD but it is comforting to know everything will soon come to a halt without removing any more fingers.
Pause OTOH implies a restart so it is purely a software driven thing which involves looking in to the G code future and creating a plan to get everything back up to speed. A well written pause is a joy to behold and well worth playing with

[Clive S]

Pause OTOH implies a restart so it is purely a software driven thing which involves looking in to the G code future and creating a plan to get everything back up to speed.

Why should a pause require a restart as you should just be able to do a resume with no problems. A pause is generally a controlled stop as apposed to an emergency stop which always requires a rehome etc.

[Robin Hewitt]

Why should a pause require a restart as you should just be able to do a resume with no problems. A pause is generally a controlled stop as apposed to an emergency stop which always requires a rehome etc.

Sorry I should have said UNPAUSE. I award stepper motors a speed at which I can start or stop them without losing steps. Once beyond that speed pausing and unpausing become interesting. It's tricky keeping everyone in synch. I have written it twice, once in Z80 assembler and once in C.

[Clive S]

Sorry I should have said UNPAUSE. I award stepper motors a speed at which I can start or stop them without losing steps. Once beyond that speed pausing and unpausing become interesting. It's tricky keeping everyone in synch. I have written it twice, once in Z80 assembler and once in C.

I had forgotten that you write your own control code and don't use Mach or Linuxcnc

[Robin Hewitt]

I had forgotten that you write your own control code and don't use Mach or Linuxcnc

That was unexpected. I thought the only person who listened to me was my wife, one word out of place and her jaw starts to flap.

[Neale]

Editing a post because of a missing gerund was pretty unexpected!

But back to topic - in an emergency (about to smash cutter into clamp, body part in imminent danger...) you want the machine to stop with 100% certainty and as quickly as possible. So you won't trust motion controller firmware, cutting power to driver power supply probably won't stop the machine immediately as you need to wait for output caps to discharge, and removing driver enable might not brake motors. Could cut power to drivers on output side of PSU but need chunky and reliable relay as you are switching high DC currents (possible contact welding?) and still lose braking. Could put something (TTL gates? Another relay?) in line with step signals - four of them, in my case.

This is getting a bit silly! In my case, the Pilz device sends e-stop to CSMIO (manual says this has very fast response) and cuts mains to driver PSU (via secondary relay). These use high-reliability n/o Pilz contacts. I am also using the auxiliary n/c contact (not high-reliability) to switch the enable signal. This is for convenience as the drivers are effectively active-low on the enable input so I need to put +5V on them to disable. So, I have two not-absolutely-reliable stopping mechanisms but which are independent so one should work when needed with cutting driver power as a slower-acting backup, but not clear at the moment if I shall get motor braking. Safety is such a compromise...