E Stop Wiring

I have wired the Mesa 7i76e all up but have just a quick question about my E stop...do I wire the E stop normally open or normally closed? I read a couple post about using the NO side wired to the input of the board which would trigger in software and then using the NC side to break one of the 24v field power wires to kill power to the board. Is this correct? Is there a configuration parameter that specifies NO or NC when wired to the input? Thanks, Andy

NC is the safer way to do it
but it is up to you to do it as you like
if you are the only one user of the machine it does not matter

If you hard wire your switch to drop AC Power to the motor power supply when pushed and then send +24v back to a 7i76e input to tell Linuxcnc estop has happened. Most estop switch are set up to allow this (NC one side, NO the other).
Each input has a matching -not pin in linuxcnc.

Ok great, thanks guys

I pondered this some time ago when I completed my last retrofit.

This machine used the encoder output from the Chinese AC servo drive as feedback.

When you use the EStop to cut power to the drive, you lose encoder feedback. This can cause errors of a couple of counts everytime you hit the EStop. If you slam the EStop during motion, it is significant and you have to re-home.

Any ideas on the safest method in this case?


Also, cutting 24v power to the Mesa board is not good AFAIK.

Henk