Stepper motors keep starting and stopping

[JAZZCNC]

The steps per setting I have used is what was outlined in the illustrations provided with both the motors and drivers. The micro steps are set at 1/8. On my drivers this corresponds to off on off.

Ok well 320 is ok but it should be worked out accourding taking linear pitch into account. With 1600ms then 320 would mean 5mm pitch. If your not using 5mm pitch and just bench testing then try 160 in steps per which would be like 10mm pitch and it's less work for the Parallel port to reach the same velocity.

This won't be your problem but it's a good starting point.

To help the parallel port you could also turn the micro stepping down on the drives to 1/4 (800ms) and set the Steps per 80.
Some times due to resonance you have to play with the MS to find best setting to match your motors. The quality of the drives plays a big part here and also how ridged the machine is. Hence why often Steppers don't work well on the bench.!!

EDIT: Ok well after seeing the drives then I'm not one bit surprised. Sorry to say this but they are Cheap nasty units which won't have much if any resonance handling capabiltys so it's no surprise motors are complaining.! They also often have slow electronics so it could be a timng issue.

One thing I've seen work before with these cheap drives is to toggle the Step low Active setting. (it's technical so won't get into why, just try it)
Also playing with Step Pulse Dir Pulse may be needed because the Opto's could be Slow so the Step pulse needs widening.
First try setting the Step pulse to 5 and Dir pulse to 0 and see what happens then if no change then toggle the Step Low Active.