Yaskawa Absolute Encoder and Mesa Hardware

Hi,
I'm retrofitting a 5 axis cnc router.
Mesa Hardware: 7i92TM, 7i77, 7i74, 7i84
Yaskawa Servo Drives: SGDH.

3 axis (X, Y, Z) use incremental encoders. these axis have home switches and they are working fine.

2 Axis (B, C) use absolute encoders and doesn't have home switches. I have connected channel A, B & C to mesa 7i77. It works like an incremental encoder. Drive also transmit Absolute position data on channel S, This data can be captured with simple python script using RS-232 Serial port connected to channel S.

Servo drive manual says that this data is (RS-422 or equivalent).

Is it possible to connect channel S to any mesa card to capture the absolute position data from the servo drive and update the joint position data while homing the other 3 axis.

Any suggestions?

Thank you.

   

 

Phase C should be the index pulse, the Phase S signal is rs422 absolute data IIRC. the index pulse should come up 1x per revolution. With home switches this is just as good as absolute encoders. The only real benefit to absolute encoders IMHO is the way they remeber position during power cycling. With good home switches and a index, the positional repeat is as good as absolutes in 99% of cases afaict

It's conceivable but likely would need special firmware
and driver changes

Probably the easiest thing hardware wise would be to read the absolute
position at startup on the A encoder pair with a special encoder module
with a built in UART. The initial position data is  at a low enough baud rate
that the encoder multiplexing would not significantly affect the serial data
stream.

Hello Gurpreet!

Could you please share whole pdf document? I am struggling with Yaskawa incremental encoders and their C channel in particular because at least those encoders I have use the C channel to commutate rotor position. And it seems that your manual might be useful.