5i25 w/ 7i76 ferror when feed>12000mm / min
- guymalpass
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01 Mar 2014 00:54 #44263
by guymalpass
5i25 w/ 7i76 ferror when feed>12000mm / min was created by guymalpass
Hi, I have linuxcnc controlling a gantry style router driven by stepper motors through the 5i25 7i76 combo. The problem is I have to limit linear axis speeds to approximately 12000mm/min or I get a following error on whatever axis exceeds that speed. Things I have tried:
While in PNCconf I've had the axes travelling at 50000mm/min but within linuxcnc I can't get above 12000mm/min. Any help/pointers would be much appreciated.
Many thanks,
Guy Malpass
- Reducing acceleration (usually I have it at 4000 but I've set it as low as 100 to see if it made a difference
- Changing ferror and min_ferror (usually I have these at 0.5 and 0.05 respectively but I've tried as high as 50 with no success
- Changing the scale to force faster step rate / axis speeds, this works so the Mesa cards are happy outputting faster pulses
While in PNCconf I've had the axes travelling at 50000mm/min but within linuxcnc I can't get above 12000mm/min. Any help/pointers would be much appreciated.
Many thanks,
Guy Malpass
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01 Mar 2014 01:20 #44265
by andypugh
The only way that a stepper system can trigger a following error is if the step generator is limited to less than the requested frequency.
If you look at Machine->view HAL configuration and look at the hm2_5i25.0.stepgen.00.maxvel and hm2_5i25.0.stepgen.maxaccel parameters (or pins, I can't recall which tab they are in) what numbers do you see?
The numbers are in units/sec and units/sec.sec and need to be a little higher than the motion planner numbers.
Replied by andypugh on topic 5i25 w/ 7i76 ferror when feed>12000mm / min
The problem is I have to limit linear axis speeds to approximately 12000mm/min or I get a following error on whatever axis exceeds that speed.
The only way that a stepper system can trigger a following error is if the step generator is limited to less than the requested frequency.
If you look at Machine->view HAL configuration and look at the hm2_5i25.0.stepgen.00.maxvel and hm2_5i25.0.stepgen.maxaccel parameters (or pins, I can't recall which tab they are in) what numbers do you see?
The numbers are in units/sec and units/sec.sec and need to be a little higher than the motion planner numbers.
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- guymalpass
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01 Mar 2014 01:42 #44266
by guymalpass
Replied by guymalpass on topic 5i25 w/ 7i76 ferror when feed>12000mm / min
Thanks Andy, the the maxvel was set at 208.3 which per minute equates to 12480mm/min !! Embarrassingly enough I have no doubt set that figure myself at some point. I am very grateful!
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01 Mar 2014 05:04 #44270
by jtc
Replied by jtc on topic 5i25 w/ 7i76 ferror when feed>12000mm / min
I don't have any experience with steppers motors, but what was the rotation of the motor at 12000 mm /min? As far as I know steppers don´t like high rpm's, so it's possible this happen if the motor can´t archive this velocity.
just one idea.
João
just one idea.
João
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01 Mar 2014 18:05 #44288
by guymalpass
Replied by guymalpass on topic 5i25 w/ 7i76 ferror when feed>12000mm / min
Hi Joao the rpm at 12000mm/min would be about 800. I have high voltage stepper drivers that allow me to run the motors at about 1200rpm while still providing the torque I need. I am actually considering getting some Stoegra step motors with a torque curve that will let me go to about 2100rpm resulting in about 31000mm/min. This is at 1/4 microstepping by the way. If I was to build another machine I would probably go down the servo route.
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