Re: Digest Number 240

Bill Wainwright wrote:

> From: Bill Wainwright <billmw@...>
>
> If you are looking for a way to interface EMC or any other step and direction
> output software to your amps, I have circuit that might help to do this without
> the need for the Servotogo card. although the Servotogo card is a more powerful
> solution than the circuit I am referring to, it is quite a bit more expensive.
> I bought a pentium 100 for $85 at boeing surplus and Dan Mauch from
> Camtronics, loaded linux and EMC on it for me and it was making my motors
> turn in no time at all.

But, I believe the original message was about running a servo system, not
steppers, with direct analog drive, not a step/direction to servo conversion.

> > [Yes, this does sound like what I need. I am definitely interested. I think
> > the servos and amps are still functional, so all I'd need would be EMC -
> > preferably loaded onto a computer and working, with a CD "rescue disk" as a
> > backup, a STG board, the Estop board you mention, wires and cables, and

Jon

Unless you Are turning the motors at a very slow rate the motors with the
step and direction to servo control move very smoothly just like a servo
system. There is no velocity feedback so the motors move in discrete
increments but my machine is set up with a resolution of .0001 inches
so it is fairly smooth. At higher speeds the mechanical time constant
of the motor tends to average the jerkiness out. The electronics consist
of two counters that keep track of the commanded position and the real
position and then outputs an analog signal equal to the difference.