Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: ostie01 on March 04, 2016, 11:29:05 AM

Title: Possible to send pulses directly to stepper driver while connected to a BOB
Post by: ostie01 on March 04, 2016, 11:29:05 AM

When to axes are slaved, is it possible to send pulses directly to one of the stepper driver with push button for some fine adjustment.

I would probably need two push button, one for step and one for direction.

Nothing to worry about the bob connected to the stepper driver?

Thanks, Jeff

Title: Re: Possible to send pulses directly to stepper driver while connected to a BOB
Post by: stirling on March 05, 2016, 07:02:27 AM

I suppose so yes - but don't be tempted to just to add a button in parallel with your current step/dir lines - you'll short your outputs.

Off the top of my head (i.e. not tested) you could do it with a couple of XOR gates but you'll need to deal with switch bounce as well. Maybe use a couple more outputs and screen buttons instead of real buttons to avoid the bounce issue.

Title: Re: Possible to send pulses directly to stepper driver while connected to a BOB
Post by: Tweakie.CNC on March 05, 2016, 07:39:58 AM

Just rambling…

It’s probably way OTT for your application but I had a similar situation a while back and after much experimentation and thought settled on a system of using two stepper motors driving one axis through a differential gear arrangement. One motor (controlled by Mach) did all the work of driving the axis and the other motor (controlled by a plc driven by sensors) made the corrections.

Just something to think about, perhaps ?

Tweakie.