Ok, ignoramus here. Let me go on the record and say I know very little about controlling stepper motors. I have a Centent CNO142 (CN0142 & CN0143 Microstep Drive) microstep drive controller and a Vexta 1.8 deg 1.4v 3.8A 2-phase stepper motor that I'm trying to get to work together in a standalone application. I pulled these two items from a piece of working equipment, so I know they are compatible. To generate a step input for the CNO142 I built a simple 555-based pulse generator (The 555 Astable Circuit - More Detail) The pulse generator is powered from a 6v DC supply, the CNO142 from a separate 24v DC supply.

When I power everything up, the motor "pulses" almost in place, not moving in one direction. It'll take a step or two one way, then back the other way, then vibrate in place and not seem to move at all. If I adjust the speed of the pulse output on the 555 circuit, the speed of the motor pulse varies accordingly, so I think the CNO142 is correctly seeing the step input and the 555 pulse generator is working OK. But why does the motor not turn in the same direction continuously? I suspect it has something to do with the fact that I have nothing connected to the DIRECTION input of the CNO142, but I'm not sure what to connect it to. I've tried connecting it to both + and - of the pulse generator power supply, but neither made any difference. What am I doing wrong? Thanks!