Stepper motors should hold position when error.
- LeonDolnicar
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29 Sep 2025 19:26 #335565
by LeonDolnicar
Stepper motors should hold position when error. was created by LeonDolnicar
I am running a 3 axis CNC mill with stepper motors, through a 7i76eu card running linux CNC. Currently when one of the motor drivers gets a fault, the motor lose all power. This is problematic for the Z axis, which uses a stepper motor with a brake. When its driver gets a fault the brake is engaged, but there is a delay, in the meantime the z axis is in free fall for about 10cm. Is it possible to program the stepper drivers in such a way that when they get a fault they stop the motors and hold the position.
Thank you for all the answer and suggestions in advance.
Thank you for all the answer and suggestions in advance.
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- tommylight
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29 Sep 2025 21:51 #335573
by tommylight
Replied by tommylight on topic Stepper motors should hold position when error.
How does LinuxCNC/Mesa know there was a fault?
If drives have fault out, there might be something we can do, but for now i am out of commission as i spent the whole day chasing python scripts to output gcode for 3 and 4 axis machines from some really obtuse files some proprietary software outputs.
If drives have fault out, there might be something we can do, but for now i am out of commission as i spent the whole day chasing python scripts to output gcode for 3 and 4 axis machines from some really obtuse files some proprietary software outputs.
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- LeonDolnicar
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19 Oct 2025 08:38 #336699
by LeonDolnicar
Replied by LeonDolnicar on topic Stepper motors should hold position when error.
Faults from stepper drivers are wired as inputs on mesa card. When fault is triggered mesa triggers emergency stop.
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- PCW
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19 Oct 2025 13:07 #336704
by PCW
Replied by PCW on topic Stepper motors should hold position when error.
Does the drive itself power down on a fault?
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- LeonDolnicar
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21 Oct 2025 15:06 #336835
by LeonDolnicar
Replied by LeonDolnicar on topic Stepper motors should hold position when error.
Yes,
the motor driver detects the fault and sends the signal to the the mesa. When driver detects the fault it also disables the motor (causing the z axis to fall). What I want is for the driver to stop the motor and hold position when it detects a fault not disable it.
the motor driver detects the fault and sends the signal to the the mesa. When driver detects the fault it also disables the motor (causing the z axis to fall). What I want is for the driver to stop the motor and hold position when it detects a fault not disable it.
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21 Oct 2025 15:35 #336836
by PCW
Replied by PCW on topic Stepper motors should hold position when error.
Can you change the drives disable behaviour?
If not, is there a way to reset the drive?
If not, is there a way to reset the drive?
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- LeonDolnicar
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21 Oct 2025 16:08 #336838
by LeonDolnicar
Replied by LeonDolnicar on topic Stepper motors should hold position when error.
That is what I am trying to figure out. I searched online but found nothing.
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21 Oct 2025 16:20 #336840
by PCW
Replied by PCW on topic Stepper motors should hold position when error.
Can you reset the drive by disabling and immediately re-enabling the drive?
That is something that could be done in hal (at least for Z)
(assuming you have the drive enable connected)
That is something that could be done in hal (at least for Z)
(assuming you have the drive enable connected)
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- rodw
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21 Oct 2025 19:20 #336846
by rodw
Replied by rodw on topic Stepper motors should hold position when error.
This is dependent on the outputs and inputs of the stepper driver you are using. Can you share more?
Personally, I don't think you can achieve what you want.
But getting faults on the drive implies an incorrectly set up stepper. Fix that and the problem goes away.Try reducing the current on the drive.
Personally, I don't think you can achieve what you want.
But getting faults on the drive implies an incorrectly set up stepper. Fix that and the problem goes away.Try reducing the current on the drive.
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- LeonDolnicar
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21 Oct 2025 19:48 #336850
by LeonDolnicar
Replied by LeonDolnicar on topic Stepper motors should hold position when error.
I have built my CNC just this month so I have only conducted test cuts, and have not gotten a driver error while machining yet, i just thought such a setup would make more sense if it did happen.
How are errors on drivers on CNC mills usually set up.
I am using Motor Driver CL-HSS860 driver with nema 34 stepper motor.
How are errors on drivers on CNC mills usually set up.
I am using Motor Driver CL-HSS860 driver with nema 34 stepper motor.
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