Servo driver selection

Well I've been having a bit of a dig around on the net and found this page

http://www.beisensors.com/crossover-index.html

going then to Fanuc page

http://www.beiied.com/crossover/fanuc.html

it shows the Fanuc A86O replacement is an H29 (The link doesn't work)

but the data sheet can be found here

https://www.yumpu.com/es/document/view/46615791/model-h29-incremental-encoder-pdf

As Jon said looks like standard A B Z output. Are the commutation signals sent from more sensors that are not part of the actual encoder?

Gatesy wrote: Well I've been having a bit of a dig around on the net and found this page

http://www.beisensors.com/crossover-index.html

going then to Fanuc page

http://www.beiied.com/crossover/fanuc.html

it shows the Fanuc A86O replacement is an H29 (The link doesn't work)

but the data sheet can be found here

https://www.yumpu.com/es/document/view/46615791/model-h29-incremental-encoder-pdf

As Jon said looks like standard A B Z output. Are the commutation signals sent from more sensors that are not part of the actual encoder?

This is a plain quadrature plus index encoder, it provides NO commutation signals. So, it cannot be used with most systems, as they would have no idea which coils to energize to get it moving right at power-on. There are what are called "six channel" encoders, that provide not only ABZ, but "Hall signals" too. But, then these would need to be "phased" to the motor magnets, which is a little tricky.

The Fanuc encoders are quite good, unless you drop the motor they rarely go bad. And, I have the converters for both main flavors of the Fanuc encoders.

Also note that these encoders are mechanically in NO WAY a drop-in replacement for the Fanuc encoders.
You would have to make a mounting adaptor and a shaft coupling.

Jon

Ok thanks.

Time to weigh up the options I think

Many thanks for all the help

Another quick question. Can LinuxCNC be used to provide a closed loop system when it is used with stepper motors? I assume this would be a sort of dumb stepper driver that keeps stepping until LinuxCNC tells it to stop, rather than telling it how many steps to take?

Gatesy wrote: Can LinuxCNC be used to provide a closed loop system when it is used with stepper motors?

Stepper motors are not really suited to any sort of closed-loop operation unless it is very tightly integrated to the motor. But it rather depends on what you want to do.
It is perfectly possible to run steppers in velocity mode with a PID closing the loop on linear scales, for example.

Replacing the Fanuc servos with steppers would be a terrible idea....

No they're not to replace the servos!!!

I have a little Conect Cadet lathe that needs a control system, so thought I'd put LinuxCNC on that, it has old steppers on it, would like to put servos on it but they would need to be tiny, so just wondered if you can do feedback with steppers. I'll be replacing the steppers with new ones or servos

Gatesy wrote: Can LinuxCNC be used to provide a closed loop system when it is used with stepper motors? I assume this would be a sort of dumb stepper driver that keeps stepping until LinuxCNC tells it to stop, rather than telling it how many steps to take?

Yes, this can be done. The Pico Systems Universal Stepper Controller can read an encoder to sense position. Normally, it counts it's own step pulses and supplies that back to LinuxCNC - that is the typical open-loop mode.
But, by flipping a DIP switch on the board, it can read an encoder instead. This does not make the stepper unstallable, but will correct occasional lost steps. It will also alert LinuxCNC when a motor stall has ocurred, so ALL axes will stop. When a motor stalls, you would NOT lose your position alignment as would happen in the open-loop mode.

Jon

Jon