Spindle on/off under CNC software control - safety worries!

[JAZZCNC]

If you're worried about not switching something back on, for the interlock, use a switch with an extra contact, or wire in an extra relay, and have it connected to an additional input, then set up the controller to prevent it from restarting until it sees the additional input, and flagging up if the interlock isn't closed.

Isn't that just the same has what I said in post #5.?

[Wombilly]

as an ex employee of www.emachcnc.com we used to use m3 to turn on spindle and m5 to turn it off, the output from the controller switched a relay, for added safety we supplied the inverter via a contactor, whose coil was switched via a key switch, as far as the HSE were concerned, as long as the facility to remove a tool ( key ) to make safe the spindle, it was deemed safe to handle.