Controlling existing motors with resolvers

andypugh wrote:

What is the feedback system used for axis position? Are there separate scales, or does that rely on the resolvers on the motors too?
 

There aren't any other position sensors, so the motor resolvers must serve both commutation and position feedback.

In that case things may get a little complicated. It comes down to how the controller gets its position information. Often the drive will excite the resolvers, use them for commutation, and then pass a quadrature signal out to the rest of the system.

The Mesa 7i49 and (I expect) the Granite devices drives expect to be providing the excitation signal, and will typically sample position at or around the peak in the excitation signal. If the controller is also sampling this signal for position feedback then it's going to get complicated.

Do you have any details of the drive to motor and drive to contoller wiring? Is there any motor-to-controller wiring?

There is no wiring between the motors and controller: all power and signals pass through the drives. The wiring diagram doesn't help: communication to the control, whether data or discrete signal, isn't explained (i.e. wire xxx connects terminal y1 to x1, but you don't get to know what it does).

Given that I can't actually test the questionable motor properly, I think it may make more sense to replace the motors with modern servo systems.

www.kollmorgen.com/sites/default/files/p...9032002701_A_5.1.pdf
The Page-86 in above DMC2 drive manual gives general resolver specification recomended by drive

www.wittenstein.de/download/operating-manual-tpm-plus-en.pdf
The Page-36 in this manual has resolver specification used by Wittenstein motor

It uses Tamakawa Brushless resolver
www.tamagawa-seiki.com/products/resolver...martsyn-builtin.html

Resolvers are very good (and very expensive) they will never break. (the bulbs in old optical encoders would burn out eventually, LEDs tend to last longer, but can still fail)

Given that only one drive has failed, have you looked at repairing it? It's unlikely that a hybrid system of one servo under LinuxCNC control and one under original control control would work very well.

Have you asked Mesa if the 8i20 is likely to come back into stock?
Do you know the power and voltage spec of the motors?

(I am on a train on mobile data, not in a good position to look through documentation links)