Wiring a Chinese servo to a 7i77. Setup for yet another newbie

Hi again. I've got a bit of a build thread started in the cnc machines section but I have a few questions about setting up my 7i77 so I figured I'd ask in here.

I've only ever dealt with stepper systems and mach3 so this is all a big step.

Ive got my servo drive connected and setup (super basically at this point, no tuning yet) and can supply it +-10v and get rotation. There's a 60 rpm or thereabouts drift at the moment but i wont worry about that untill ive got the drive enable handled by linuxcnc and the loop closed.

I'm a bit lost on the mesa pins for the encoder vs the servo drive encoder outputs. The 7i77 lists, as cut straight from the manual:

TB3 PIN FUNCTION DIR

1 QA0 TO 7I77
2 /QA0 TO 7I77
3 GND FROM 7I77
4 QB0 TO 7I77
5 /QB0 TO 7I77
6 +5V FROM 7I77
7 IDX0 TO 7I77
8 /IDX0 TO 7I77

and so on for each encoder. My servo drive speed/torque wiring details an A,B and Z +- signal wire and a 'Z collector open circuit output' and ground.

You can see the wiring diagram listed on page 24, link here.

I need a bit of help getting everything wired correctly. I've read a bunch of build and setup posts and there's enough references to burnt boards to make me cautious. Probably more an issue for the field and signalling wiring but I'd still rather go at it armed with half an idea.

Any help greatly appreciated.

Cheers

Sam

Oh, and if anyone's got suggestions (or an existing example more like) of wiring the enable and reset etc I'd love to see it. I can work it out and post my plan for some feedback but if someone's got the wiring handy, you know, shoulders of giants and all that

SPH wrote: TB3 PIN FUNCTION DIR

1 QA0 TO 7I77 PA+ pin 20
2 /QA0 TO 7I77 PA- pin19
3 GND FROM 7I77 GND pin 1
4 QB0 TO 7I77 PB+ pin 18
5 /QB0 TO 7I77 PB- pin 17
6 +5V FROM 7I77 do not connect
7 IDX0 TO 7I77 do not connect
8 /IDX0 TO 7I77 do not connect

Also +-10V from Mesa to pin 25 and 13 respectively .
Drive enable from Mesa to pin 29 and 9.

Ahh, ok, so the third phase of the encoder isn't used?

Or I guess more to the point I obviously don't quite get the A,B,Z encoder outputs. I'll read up a bit.

Regardless, I should now be able to get the drive wired to the 7i77 and start trying to get things moving on the bench.

Thanks again!

The Z phase of the encoder is an index mark. It is optional, and often used to make homing more precise.

So if I connect the encoder plug to the 7i77 I get some signs of life in the axis test page when I turn the motor shaft but if I connect the TB5 drive plug with the +-10v connectors the 7i77 powers off. Comes back on if I disconnect the plug. It's a bit nerve wracking to be honest.

I've got TB5 pin 4 (AOUT0) going to pin 25 (VREF +) on the drive and TB5 pin 3 (GND) going to pin 13 (AGND) on the drive as suggested.

The drive isn't (wasn't) enabled when I connected the plug.