Run a stepper from 2 DM542 drive

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Can you be more specific? A diagram will be awesome. Thank you

I am sorry but I have no diagram. Anyway, it is a simple circuit with one switch and a relay which flips the step, dir, en and gnd signals, all four at the flip of the switch. The circuit is really simple.

I made a simple sketch and scanned it for clarity.



UCCNC generates the pulses if I flip the switch and select it, or the Arduino box if I select the lathe mode. The servo is a servo with integrated driver, but it could be a DM542 also, it makes no difference as long as the step, dir, en and the gnd can be used to control it. The relay in my case is one I had in my drawer, if you can't find one which switches all the four signals at once, you can use two, or even four separate relays as long as you switch all at the same time. Just connect the coils in parallel and you'll be fine. Of course, as I said before, it assumes that both controlling devices work independently and you don't need to rely on exact positions between each devices. In my case, I don't care where the motor stops, the lathe accelerates and decelerates to a speed I want it to, and if I use UCCNC then I have to zero the position for UCCNC, so the position is lost every time I flip the switch, but for me that's perfectly fine.

I don't know if you have seen this before, but I made a video about the control box. This is an early version, since then I swapped the stepper to a servo and built my lathe, which now can spin considerably faster.