Quote Originally Posted by Robin Hewitt View Post
If you are using opto couplers then your signal is current not voltage dependant and you are effectively proof against electrical interference.

If it isn't working you are barking up the wrong tree if you think screening and more volts is going to help.
Guess I didn't pay too much attention to the cabling, screening etc. Fact is that I get faulty signals from endstops if I run them at 5V without opto. Now I changed that to 24V proximity sensors and an opto near the BOB to ground the input pin. Now that's working.

So the stepper drivers 5V opto inputs Enable/Pulse/Direction. Those are wired single ended with common anode.
Just figured to go all in and use Line drivers where I can, and make it as stable a possible.

The MAX490 chip looks perfect, if I read the specs. right. Then it can drive an opto directly (20mA) ?

Thanks again, Bo Andersen.