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glass scale on MPG input/OAK

Posted: Sun Jan 07, 2018 6:15 pm
by tblough
Well, I'm trying something a little out of the ordinary. I'm trying to hook a glass scale up to the MPG encoder inputs on my OAK board. I think I've set everything correctly, but obviously not as I'm not displaying any encoder activity on the encoder screen.

I've set parameter 314 (Axis 7 encoder) to 15 for the MPG input. I have another glass scale (X) on encoder 5 so I've set parameter 259 (Manual axis) to 2^4+2^6 = 80 to make axis 5 and 7 manual axis, and I've set up the motors as below:
Unfortunately the encoder screen does not show any activity on axis 7.
Does anyone have any ideas what I'm missing? Also, what is the field DQOA on the Encoder screen?

Re: glass scale on MPG input/OAK

Posted: Mon Jan 08, 2018 3:23 am
by cncsnw
The DQOA column indicates what errors have been detected on that encoder. I don't know off the top of my head what 'O' and 'A' signify, but 'D' and 'Q' are for Differential and Quadrature errors.

The 1 in the D column for your W encoder indicates a differential error: either your A and /A pair, or your B and /B pair, or both, are not being driven to opposite states. Somehow you will need to get a meter in there and measure the voltage between the 0V common and each of the four channel wires.

Ideally do these measurements on the Oak board itself, so if the problem is with one of the tiny JST crimp contacts, you will find out.

Re: glass scale on MPG input/OAK

Posted: Wed Jan 10, 2018 11:46 am
by tblough

Haven't had a chance to do any further debugging yet. Next step is to pull the MPG off the mill and hook it up to the MPG port on the lathe and verify that I am getting activity. If that's good, I'll start debugging the cable. I'll keep you posted.

Thanks for all your help.

Re: glass scale on MPG input/OAK

Posted: Thu Jan 11, 2018 10:32 pm
by tblough

Seems like the idiot married to my current wife couldn't wire a simple DB9 connector. No problems with the tiny crimps in the MPG connector but he transposed 2 pairs in the DB9. Wires swapped and we're cooking with gas now!

Oak with two servos, dual handwheels, X & Z glass scales, and spindle encoder. Any tips on setting Deadband and Velocity to get these scales dialed in?