Inductive Limit Switch problem

[Kitwn]

I'll stick with my self-centred view of having BoBs and similar with opto-isolated inputs. I've never been a fan of distributing a high speed logic input signal into the big, bad world.

I'm in complete agreement with you on that one, but the logic following it probably needs to be slightly different from the input circuit to my cheapo card. Something with a supply voltage well above 5V would be a good start.

EDIT: Been doing a bit more looking at opto-couplers and there certainly is a big range of options. The Darlington output types have a higher saturated output (up to 1V) compared to the conventional type (as low as 0.1 - 0.2V at low current) so you really must choose your device, but there are devices that would interface successfully to the cheap card. Since this application is at a guaranteed very low frequency I'm happy to let old technology do the job this time.