Servo Oscillation Issue at ±6.6V 5i25 + 7i77, Analog Control

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15 Feb 2025 19:14 #321656 by PCW
That looks like maybe an electrical/wiring issue with the encoder.

Is differential signaling used?
 

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17 Feb 2025 16:39 - 17 Feb 2025 16:49 #321846 by Traken
Yes, it is a differential signal.
I am attaching a screen manual from the servopack.
 
 Two servos are Delta asda-b2 750w and one on the z axis is the Chinese a1-svd 750w and in total there are such symptoms on each axis.
The encoder cable is shielded and a separate analog cable is also shielded, the shield is only connected to the servopack.
Maybe I need to use resistors?

 
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Last edit: 17 Feb 2025 16:49 by Traken.

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17 Feb 2025 19:12 #321856 by PCW
Is the 7I77 jumpered for differential inputs?

It may be a noise issue. One way to check if it's a common mode noise issue
(noise that exceeds the common mode range of the RS-422 receivers)
is to enable encoder error reporting:

setp hm2_5i25.0.encoder.00.quad-error-enable true

Once this has been done, inputs that violate the quadrature sequence
(often noise will do this) will set the quadrature error flag:

hm2_5i25.0.encoder.00.quad-error



 

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20 Feb 2025 12:07 - 20 Feb 2025 12:19 #322049 by Traken
It checks your method and shows no error. I will try to turn on linuxcnc and control from the servopack to read a higher speed and exclude the encoder reading.
Because it still seems to me that it is not related to the encoder reading but to the analog power supply.
What still surprises me is that if I drive the axle in the positive direction, I can achieve 10 m/min, and if I drive the axle in the negative direction, 8.3 m/min.
Last edit: 20 Feb 2025 12:19 by Traken.

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20 Feb 2025 14:56 #322074 by PCW
It sure looks like an encoder issue, especially the speed limit
(in one plot the encoder velocity dropped to 0 in basically an instant)

Did you set the encoder filter to 0 on all encoder channels?

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21 Feb 2025 06:16 #322169 by Traken
No, I set it on one axis I was testing. Should I set it on all axes?

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