Newbie from NZ

[Doddy]

Thanks I would appreciate a diagram when you have the time don’t really understand the relay-diode thing but maybe I see it I can do it
Richard

Okay, hand-cranked over lunch. This is a very basic solution - I think you'd really be looking at a three button solution (the third being a "stop" button in case things went pear-shaped). But understand this one first...

SW1 and SW2 with open/close the sled. Not sure which will do which - everything depends on the wiring to the motor. Lets assume SW1 opens, and SW2 closes.

SW1 is pressed. The speed controller (central box) presents a PWM signal to the motor (M) with e.g. negative on M+ and positive on M-. That allows D1 to forward-conduct and RLY1 is actuated, closing the NO contacts within that relay. These are wired across the SW1 button pins, and essentially keep the button pressed whilst the motor remains driven. At the end of the travel, the proximity switch (not shown) causes the controller to stop driving the motor, and the voltage across M+ and M- falls to nothing. The motor stops, and the RLY1 de-energises, releasing the "Open" command.

Now, operator presses SW2 to close. The speed controller presents the PWM signal to the motor with positive on M+ and negative on M-. That allows D2 to forward-conduct (D1 is reverse-biased and does NOT conduct). That closes the NO contacts within that relay, wired across the SW2 button which keeps the button "pressed" whilst the motor remains driven to close. At the end of the travel the proximity switch (also not shown) commands the controller the stop driving the motor and the voltage across M+ and M- falls to nothing. The motor stops, and the RLT2 de-energises, releasing the "close" command.

Note, I'm making assumptions against the polatity of the PWM output to the motor depending on whether SW1 or SW2 is pressed. It's 50% certain that I've assumed wrongly and you'd have to reverse both D1 and D2 to get the circuit to work correctly.

Now, a third (stop) button?, would be very useful for when the sled jams and can't complete the traverse. You probably wouldn't want to interrupt the supply to the motor (big currents, inductive load = lots of wear-and-tear on the contactor) - but a suitably heavy duty relay could be used in-line with the output from either M+/M- from the controller - a NC contactor breaking either the M+ or M- signal, with the relay coil actuated by the "stop" button. You could also fiddle with a smaller relay with two NC contacts to break the signalling into the INPUT SIGNAL 1/2 inputs (actually, if the "NEGATIVE SIGNAL" on SW1 and SW2 are common for both switches, then you'd only need one NC contactor here... or a NC push button).