Re: deskcnc servo driver

Greg:

Remember that the G320's emulate a stepper control system but use
servo motors with shaft encoders. The software "thinks" it's driving
stepper motors. This is almost always an open loop system where the
control software "trusts" that the motors have done what they were
told to do. In this context the software never knows if the motors
have done what they were supposed to do.

That's why the G320 has a fault signal to say, hey, I did not do what
you said. Some industrial controllers are closed loop systems and have
position information from some sensing device other than the motor
controls. See comments interspersed in your questions.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Gregory Kamysz <smsupply@a...>
wrote:

> So these errors are best avoided by using motors that are strong enough
> to keep up with the feeds or feeds low enough that the motors can

handle?

Yes, the motors must be able do execute the commands in the time alloted.

> Setting the gain and damping on the Gecko 320's will also come into
> play. What is the best way to do that without access to a scope?

I have NEVER setup servo motos without a scope so look to someone else
for that answer.

> Am I correct in thinking that these issues mostly come into play when
> making heavy cuts at high speed?

Not generally, they will matter for all motion commands. However, if
cutting motions place more load on the servo than it can handle at the
commanded speed then this will be a problem.

> Sorry, about the questions, I'm an info junky.

Keep on asking the questions, that's how one learns. A note about the
128 count fault limit for the G320's. That's the value I would have
chosen myself. Most encoders used it this application are about 500
counts per revolution. If you have 5 pitch ball screws (common) then
that's about 0.0004" error before it faults, not a problem for most
folks. The right question is why does it fault at all. Something is
wrong with the design.

Regards;

Ken