I can't reverse the spindle rotation.

ok this is driving me crazy. today i fired up the machine, turned on the spindle, hit reverse... and it worked. first time since swapping to the 7i92.

i thought maybe the gremlins had left, so i shut down the machine, powered it back up again, tried reverse — nothing. spindle just keeps going forward. led on the module still lights up, wiring is solid and untouched. literally didn't touch a single wire between the time it worked and the time it stopped.

any clue what could cause this?

Deleted as i missed the 5V to 24V level shifting mentioned above.

What do you recommend I use instead?

I would check the output of the direction control PC817 with a voltmeter/ohmmeter

PCW wrote:

I would check the output of the direction control PC817 with a voltmeter/ohmmeter

I checked for continuity between the V output and GND using a multimeter, and even though the LED is lit, there is no continuity. 


Tomorrow I’ll check the resistance at the output. It’s all very strange because I have two brand-new modules, and they behave the same way. 

They always worked perfectly on a parallel port, but I no longer have the PC with a parallel port to test them again...

Deleted as i missed the part about level shifting.
Sorry.