[danande]

Hi,

How have you wired your ESD to your CNC lathes and mills?
I have a cnc mill, and I'm wondering what is the best way to do this in a safe way.
Using smoothstepper, cnc4pc c32 bb, gecko 201, and a lenze vfd.

I do not think using the esd switch to trigger esd signal in mach3 is the safest, and relying on that the software will shut down the machine.


So the safest way is obviously to use esd switch to break the connection to a ''master'' relay that gives power to other relays, so pressing esd makes all electrical components dead, vfd, cnc control-everything. But this defeats the purpose of the esd function in the mach 3.

Another option is doing the same but leaving power for computer, and cnc components, but still cuts power to a relay for the DC PSU to the stepper motors. Maybe this is the best solution. Mach3 would still be in control and would detect esd signal. But I'm not sure what would happen to drives if I do this, is it bad for them? Could they still run a little on power from the caps in the psu, even after power is lost?

A third option is using esd to cut power to a main relay to vfd, and keep powering the cnc electronics, but then you rely on electronics to stop your machine moving - this is not as safe, but is probably safe enough for plasma-tables and such.

ESD should only be used in emergencies after all, so I guess I've answered my own question here, by cutting all power to everything would be safest.

What are your thoughts, how are professional machines wired?

[Al_The_Man]

Many previous posts here on the subject.
Under NEC and NFPA 79, which is basically the same as the IEC codes, The E-stop can be software initiated via Charge Pump or Watch-dog timer but never software based.
As a minimum, the E-stop string is hard wired, usually 24vdc or lower, and all alarm devices, charge pump, O.T. L.S's, Stop P.B.'s etc are AND'ed or in a series string with a control relay as the output, The relay then shuts off power to any and all motorized devices.
Controller, input devices and displays can be left powered.
Here is a couple of references.
http://www.automation.siemens.com/do.../emv_r.pdf?p=1

If an external E-stop takes place, the Mach stop input should be activated to inform the controller.
Al.