HM1 Home Switch triggered by motor overcurrent?
Posted: Wed Jul 01, 2020 7:32 am
Hello. I have a linear application with a SOLO with the 0 position indexed by a micro-switch. When I drive the motor in reverse toward the micro-switch in Motion Studio PWM control with the motor under no load, everything works as expected - the micro-switch is hit, S3 goes to 0V and HM1 is triggered in Motion Studio - encoder is zeroed, so far so good!
The problem arises when the motor is under load - under certain load, the motor stops and HM1 is triggered - zeroing the encoders, etc as if the micro-switch was hit - but it was not!
To confirm S3 was not hit, I put an oscilloscope on S3 and GND - since there seems to be a pull-down active internally, with my external pull-up - the voltage of S3 is 2.7V when open, 0V when closed. The motor adds about 1.2V Peak-Peak noise ripple during movement, the minimum voltage measured on the scope was 2.2V - well above the logic zero of the micro-controller, which I would guess to be about 0.7V.
Moving the motor up and down does produce noise on S3, but I would think not enough to trigger HM1.
So, what is triggering HM1 then?
If I set S3 to E-Stop instead of Home - this problem goes away - meaning my pull-up is good and motor noise doesn't seem to trigger it - but then it no longer functions as a Home switch.
This leads me to believe it's in the firmware of the SOLO.
My guess is an internal motor protection in the firmware?
Does the SOLO firmware contain some current threshold above which it will consider that the home has been hit, even though S3 is still high? If so, can it be disactivated?
Troubleshooting, I set the M1 max current to something like 1A, this seems to work as blocking the motor only triggers OC1 and no longer seems to trigger HM1 - unfortunately this does not give me enough power for my application.
Configuration:
Power Source: 4S LiOn
Motion Studio has S3 set as Motor Home(User)
S3 has external pull-up to 5V through 4K7
S3 drops to 0V through microswitch
Motor current limit is 2.5A (motor peak is 7A)
Thank You
The problem arises when the motor is under load - under certain load, the motor stops and HM1 is triggered - zeroing the encoders, etc as if the micro-switch was hit - but it was not!
To confirm S3 was not hit, I put an oscilloscope on S3 and GND - since there seems to be a pull-down active internally, with my external pull-up - the voltage of S3 is 2.7V when open, 0V when closed. The motor adds about 1.2V Peak-Peak noise ripple during movement, the minimum voltage measured on the scope was 2.2V - well above the logic zero of the micro-controller, which I would guess to be about 0.7V.
Moving the motor up and down does produce noise on S3, but I would think not enough to trigger HM1.
So, what is triggering HM1 then?
If I set S3 to E-Stop instead of Home - this problem goes away - meaning my pull-up is good and motor noise doesn't seem to trigger it - but then it no longer functions as a Home switch.
This leads me to believe it's in the firmware of the SOLO.
My guess is an internal motor protection in the firmware?
Does the SOLO firmware contain some current threshold above which it will consider that the home has been hit, even though S3 is still high? If so, can it be disactivated?
Troubleshooting, I set the M1 max current to something like 1A, this seems to work as blocking the motor only triggers OC1 and no longer seems to trigger HM1 - unfortunately this does not give me enough power for my application.
Configuration:
Power Source: 4S LiOn
Motion Studio has S3 set as Motor Home(User)
S3 has external pull-up to 5V through 4K7
S3 drops to 0V through microswitch
Motor current limit is 2.5A (motor peak is 7A)
Thank You