Centroid Community CNC Support Forum

"in response to positive PID output" - what happens if the PID output is "OFF" instead of a number?

When the PID output is OFF, no current flows to the motor, and no torque is applied in either direction.

When your motor is running away, the PID output is not OFF. It is either positive or negative, probably very briefly maxed out at +127 or -128. However, as soon as the runaway is detected, the control removes power from the axis and from the drive. By the time you take a picture of the screen, the output has reverted to OFF.

Try swapping the motor power leads on terminals 3 and 4 of the servo drive (i.e. swap Y+ with Y-). Then see if you can jog it without getting a runaway. Also see whether, when you do that, the axis jogs in the correct direction, or whether motion is reversed.

cncsnw wrote: ↑Sun Oct 08, 2023 12:25 am

"in response to positive PID output" - what happens if the PID output is "OFF" instead of a number?

When the PID output is OFF, no current flows to the motor, and no torque is applied in either direction.

When your motor is running away, the PID output is not OFF. It is either positive or negative, probably very briefly maxed out at +127 or -128. However, as soon as the runaway is detected, the control removes power from the axis and from the drive. By the time you take a picture of the screen, the output has reverted to OFF.

I found that to be the weird part. I had to record a phone/video recording thinking I might miss something if I had to blink/look away.
On the Z+ jog the PID switches from OFF to 2 but then on the Y+ jog I think I hear the power being cut to the motor almost the same time the errors show up on the screen while PID appears to remain OFF.

https://youtube.com/shorts/m-_NpHLRUkk

cncsnw wrote: ↑Sun Oct 08, 2023 12:25 am Try swapping the motor power leads on terminals 3 and 4 of the servo drive (i.e. swap Y+ with Y-). Then see if you can jog it without getting a runaway. Also see whether, when you do that, the axis jogs in the correct direction, or whether motion is reversed.

Thanks for the continued suggestions! I really appreciate it Will try this next.

Just to clarify:
Does the motor on which you replaced the encoder, run away as soon as it is enabled, both when connected to the X axis drive output and encoder input; and also when connected to the Y axis drive output and encoder input?

And to save me the trouble of reading back through five pages of posts when I have other work to do:
Has the problem motor been taken apart and put back together (i.e. had the rotor and brushes removed from the case and then reassembled) since the last time it was known to work under control?

cncsnw wrote: ↑Mon Oct 09, 2023 2:20 am Just to clarify:
Does the motor on which you replaced the encoder, run away as soon as it is enabled, both when connected to the X axis drive output and encoder input; and also when connected to the Y axis drive output and encoder input?

And to save me the trouble of reading back through five pages of posts when I have other work to do:
Has the problem motor been taken apart and put back together (i.e. had the rotor and brushes removed from the case and then reassembled) since the last time it was known to work under control?

So this entire time we've been testing the X-axis motor on Y-axis cables ( for ease of reach ).
Once we put the X-axis motor on the X-axis cables the encoder and motor worked just fine :facepalm:

We have since then greased all the bearings, removed rust on rails and have been able to get the whole thing finally to run the home procedure and even run G/M codes

We did experience crashes with v8.23 often enough on various procedures and reverted back to v7.17 which is now working and appears to be stable.

Going to do first cut soon after we figure out what we can recover from floppy disks that haven't been used for 15+ years and of course learn how to use the Intcon software ^_^

Once we get some initial cuts and confidence it's working as expected we'll probably start thinking about how to upgrade the software and computer as you suggested long ago.

Thank you for helping us!