[sdfoiler]

Fadal experts,

I am wanting to install another estop switch on my CNC88 4020 that I can control remotely. Does anyone know how the current estop switch works on the pendant? It looks like it is a DPDT switch with 5 volts on one leg and 120v on the other. Do both of those have to be switched off in order for the machine to go into ESTOP mode? I'm not quite sure what the 120v AC is for on the switch.

Any help would be greatly appreciated!

[Al_The_Man]

I am not a Fadal expert, but have worked in control systems for a long time, No1 it is very unusual now to take anything higher than 24vdc to a operator interface.
But if you have both 120v and 5v I would hazard a guess that the 120v is in series with a control or E-Stop relay in the panel, this relay usually cuts of power to spindle and drives and also advises the controller that an E-Stop has taken place.
The 5v could be anything from indicator light, to low level signal to the control?
What you could do is disconnect each in turn from the E-Stop switch and see what affects what?
The true E-stop is usually a series (N.C.) switch P.B. and all that is usually needed is to wire another NC operator in series in the string.
Al.