Servo system not moving correct distance

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12 Jan 2021 21:44 #195125 by Michael
Using PCConf I set up my encoders and axis. Everything moves fine but it is only moving approximately half the distance it should. Pitch on the screw is 8mm but when moving one revolution the encoder is reading .606" moved. The issue is consistent for atleast two axis. The 7i77 is set to differential mode for the encoder jumpers. Maybe I am missing something in the math? Noice on the encoder abling? I have grounded the shield to the 7i77 side TB3 pins 3, 11, 19 all A/B/Z signals are individually shielded but grounded to the same terminals.


Also uploaded my HAL and INI files:

File Attachment:

File Name: my_LinuxCN...1-12.hal
File Size:11 KB

File Attachment:

File Name: my_LinuxCN...1-12.ini
File Size:4 KB
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12 Jan 2021 21:55 #195128 by tommylight
Encoder lines per revolution look wrong, what is the encoder resolution or PPR? That should be written there.

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12 Jan 2021 22:01 - 12 Jan 2021 22:20 #195130 by Michael
PPR= Line Num x4
In the drive I have it set to 3937 and the pncconf seems to match the planned resolution I was shooting for if this was the case. In the appendix of the manual the line number was changed to be max 4095 and this is confirmed in the drives software. In doing some quick math though the scaling between 3937/2048 and .606/.315 is the same so maybe the manual has some conflicting typos and corrections.
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Last edit: 12 Jan 2021 22:20 by Michael.

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12 Jan 2021 23:45 #195148 by andypugh
3937 is a pretty unusual number to choose. And might even cause rounding errors. Choose a nice round binary number like 2048 or 4096.

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13 Jan 2021 19:59 #195242 by Michael
Go it figured out. Per DMM servo support you can have the PPR or Num_Line set to anything between 500 and 2048 or a single setting of 4095. Just nothing in between 2048 and 4095. Got it all re scaled and working now. Thank you for the help.

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