As much as I hate to agree with @ednisley …
This is a an RS-232 type communications (ANSI) that use a maximum of 13V, all the interfacing is in the order of a 15V supply. My laser has a 24V supply for the motors and the Ruida, but all the interfacing is ttl level i/o.
I don’t know of anything commercially that produces a differentiated signal for pwm, although it’s doable. Clearly for longer cable runs. I do it on my little micros for probably the same reason …
It’s that or an unbalanced ttl signal. That is easy to deal with.
Most of these are 0 to 10V in this configuration, in simple terms they are analog controls.
Ed probably has it right, it will be much easier to deep six the controller and the lps for one that supports a more common interface.
It will be difficult to convert all of these to analog and back in some cases. Not to mention you’d probably have to modify the grbl software to support some of these interfaces.
It’s not like you can’t do it, but time and money, I’d have to agree with Ed and replace the goodies we’ve talked about.
Good luck… keep us updated.
