Q: 24V Line driver IC

[m_c]

If you are going for differential pairs, then I wouldn't worry too much about what voltage the differential pair is running at. 5V is prefectly good for differential systems, as that's voltage what most modern CNC encoders operate at.
The key feature of differential pairs, is any noise that gets picked up, should be cancelled out by it affecting both wires by a similar amount and the differential voltage remaining reasonably constant. (This is a very basic explanation, which I'm sure Jonathon will criticise me for it!)
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If you're running single ended, then yes, a higher voltage is better, which is why industrial machines nearly always run 24V control systems.

[Jonathan]

The key feature of differential pairs, is any noise that gets picked up, should be cancelled out by it affecting both wires by a similar amount and the differential voltage remaining reasonably constant. (This is a very basic explanation, which I'm sure Jonathon will criticise me for it!)

It's a very basic concept, so your explanation is good :)

There are plenty of differential driver ICs to choose from, I used these (specifically MAX490) in my servo motor drive and they would likely be fine for the application at hand:

http://www.maximintegrated.com/en/da...ex.mvp/id/1111

[Robin Hewitt]

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.

[fabhund]

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.