Yaskawa Drive & ABS encoder

I have an application where I will be using a Yaskawa SGDH servo drive with a SGMCS motor. The motor has an absolute encoder that goes back to the drive. I want this absolute position to go back to my RMC70 motion control. Here was the suggestion from Yaskawa

Instead of using the MA axis module with the Delta Computer controller, he would use the QA axis module.

We would hook the Sigma II amplifier up to the controller, just as if we were going to control the drive incrementally.

The SGMCS motor is a 20bit, single turn absolute encoder, when used as an absolute, with send quadrature encoder pulse stream out of the drive to the controller, before allowing the servo enable signal.

This is activated by providing a 5V TTL signal to the drive from the controller, letting the drive know that it is ready to receive the pulse stream.

The is a cost effective way to enable the use of absolute encoders, without the added cost of secondary SSI encoders, or the control cards (MA)

Click to expand...

I don't see why this would not work. Has anyone done this type of thing before?

CharlesM said:

I have an application where I will be using a Yaskawa SGDH servo drive with a SGMCS motor. The motor has an absolute encoder that goes back to the drive. I want this absolute position to go back to my RMC70 motion control. Here was the suggestion from Yaskawa


I don't see why this would not work. Has anyone done this type of thing before?

Click to expand...

I don't see why it wouldn't work. Yes, it has been done before. Just zero the counts and put the RMC in disabled or open mode before the drive sends the counts. You would need a QA ( quadrature in, analog out) module instead of a MA( MDT/SSI in, analog out) module. You may be able to use the home input as the ttl input. Is the 20 bit single turn enough for your application?

I would rather have a multi-turn but I can get by with the single turn.

Is there other drive's that do this? This is a simple idea but I have not seen it before.

I don't have a Sigma II manual in front of me to verify, but, as far as I remember, that is Yaskawa's standard way of dealing with absolute encoder when using analog (as opposed to network)control. Activate the special drive input upon power-up (I beleive it is called SEN) and the drive will send quadrature pulse train back to the controller, number of pulses being equal to the current encoder position. Once the initial position has been made known to the controller, the drive can be enabled and will operate.

P.S. Multi-turn absolute is available on Yaskawa motors, but not with this type (this is a direct-drive, "pancake" motor). Just a regular incremental encoder with battery-backed memory.