Following error 6I25 - 7I77
11 Oct 2018 20:14 #118686
by andypugh
I guess there is no way to use the resolvers directly?
I use the 7i49 on both my machines, but that needs t be supplying the resolver excitation too, and I suspect that is done by your drives?
Using a non-multiplexed firmware for three encoders on the 7i77 then adding a 7i85S on the extra port of the 5i25 with 4 more full-speed encoders might be an option.
store.mesanet.com/index.php?route=product/category&path=83_87
Replied by andypugh on topic Following error 6I25 - 7I77
Luckily I has abosolute resolvers in servos, so I can check driver position against linuxcnc position.
I guess there is no way to use the resolvers directly?
I use the 7i49 on both my machines, but that needs t be supplying the resolver excitation too, and I suspect that is done by your drives?
Using a non-multiplexed firmware for three encoders on the 7i77 then adding a 7i85S on the extra port of the 5i25 with 4 more full-speed encoders might be an option.
store.mesanet.com/index.php?route=product/category&path=83_87
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12 Oct 2018 11:48 - 12 Oct 2018 11:56 #118697
by PCW
Replied by PCW on topic Following error 6I25 - 7I77
There is a possibility of noise causing missed counts. There is a long standing firmware bug with muxed encoders with the filter off. "filter-off" mode is supposed to still have a 3 sample digital filter enabled but due to a mux sampling bug, a shorter pulse can be passed through the filter. I will make up fixed firmware sometime today if you wish to see if this helps.
I also looked carefully at the maximum count rates:
5I25 --> muxed encoder filter on ~ 550 KHz
5I25 --> muxed encoder filter off ~2.7 MHz
These assume perfect quadrature, if you allow 50% distortion in the encoders A, and B pulse symmetry (duty cycle) you must divide these count frequencies by 1/2.
A to B or B to A phase errors of 45 degrees (50%) will also limit the maximum count rate to about 2 MHz in either filter mode due to the ~4 MHz input sampling rate of muxed encoders.
I also looked carefully at the maximum count rates:
5I25 --> muxed encoder filter on ~ 550 KHz
5I25 --> muxed encoder filter off ~2.7 MHz
These assume perfect quadrature, if you allow 50% distortion in the encoders A, and B pulse symmetry (duty cycle) you must divide these count frequencies by 1/2.
A to B or B to A phase errors of 45 degrees (50%) will also limit the maximum count rate to about 2 MHz in either filter mode due to the ~4 MHz input sampling rate of muxed encoders.
Last edit: 12 Oct 2018 11:56 by PCW.
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28 Oct 2018 08:22 - 28 Oct 2018 11:20 #119542
by jsskangas
Replied by jsskangas on topic Following error 6I25 - 7I77
OK
Im running indramat eco drives in all axes.
Most of my motors has multi turn resolvers, 2 motors in nikken has pulse encoders.
Drives them self use encoders/resolvers and also dual feedback is supported.
Those are capable of different operation modes like positioning, velocity, torque.
Im using them in velocity mode.
Drives emulate incremental or SSI encoder signal to output for cnc and are capable to 1MHz pulse rate output.
Interface is RS422 differential and 7I77 is configured to differential inputs and each line have 120 ohm resistor integrated in 7I77.
I made new wiring to help issue, no change in behavior.
Now every encoder line is shielded individually.
7i77 is configured for SW mode3, This is cause i need 5Vdc handwheel support. For all encoder channel filtering is enabled.
At the moment Im running 2000 pulses per rev incremental encoder output from drives.
I was testing this yesterday and found that 15000mm/min (ballscrew lead 10mm/rev) speed to be maximum where pulses where not lost.
2000puls/rev * (1500rpm/60) * 4 = 200000 Hz
At the moment Im limited to 200 kHz.
I think I should get better count rate than this....
Im running indramat eco drives in all axes.
Most of my motors has multi turn resolvers, 2 motors in nikken has pulse encoders.
Drives them self use encoders/resolvers and also dual feedback is supported.
Those are capable of different operation modes like positioning, velocity, torque.
Im using them in velocity mode.
Drives emulate incremental or SSI encoder signal to output for cnc and are capable to 1MHz pulse rate output.
Interface is RS422 differential and 7I77 is configured to differential inputs and each line have 120 ohm resistor integrated in 7I77.
I made new wiring to help issue, no change in behavior.
Now every encoder line is shielded individually.
7i77 is configured for SW mode3, This is cause i need 5Vdc handwheel support. For all encoder channel filtering is enabled.
At the moment Im running 2000 pulses per rev incremental encoder output from drives.
I was testing this yesterday and found that 15000mm/min (ballscrew lead 10mm/rev) speed to be maximum where pulses where not lost.
2000puls/rev * (1500rpm/60) * 4 = 200000 Hz
At the moment Im limited to 200 kHz.
I think I should get better count rate than this....
Last edit: 28 Oct 2018 11:20 by jsskangas.
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28 Oct 2018 11:19 #119547
by PCW
Replied by PCW on topic Following error 6I25 - 7I77
Yeah, as I mentioned you should get to ~550 KHz even with the filter on
I suspect you will need to look at your signals with a oscilloscope.
Just as a test, does the maximum rate change if you enable the filter?
Have you changed the default encoder sample frequency?
I suspect you will need to look at your signals with a oscilloscope.
Just as a test, does the maximum rate change if you enable the filter?
Have you changed the default encoder sample frequency?
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28 Oct 2018 12:24 - 28 Oct 2018 12:58 #119549
by jsskangas
Replied by jsskangas on topic Following error 6I25 - 7I77
Hello
I was wrong, my encoder count per 1 reolution vas 5000.
so it equals 500000hz at 1500rpm.
What you said was upper limit.
I included encoder capture from 15000mm/min.
This shows A and B lines.
it does show some resonation in B line.
edit:
Resonation was from my scope, channel b needed ground as well.
So no error or interference on encoder signals.
I can manage with 15000mm/min feeds.
Best thing about this is that i know what is causing this problem.
Now i can avoid it and run some long 5-axis paths without worry.
I was wrong, my encoder count per 1 reolution vas 5000.
so it equals 500000hz at 1500rpm.
What you said was upper limit.
I included encoder capture from 15000mm/min.
This shows A and B lines.
it does show some resonation in B line.
edit:
Resonation was from my scope, channel b needed ground as well.
So no error or interference on encoder signals.
I can manage with 15000mm/min feeds.
Best thing about this is that i know what is causing this problem.
Now i can avoid it and run some long 5-axis paths without worry.
Last edit: 28 Oct 2018 12:58 by jsskangas.
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28 Oct 2018 13:38 - 28 Oct 2018 13:40 #119552
by PCW
Replied by PCW on topic Following error 6I25 - 7I77
So you have the encoder filter enabled?
You should be able to get to more the 2 MHz with the filter off
You should be able to get to more the 2 MHz with the filter off
Last edit: 28 Oct 2018 13:40 by PCW.
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28 Oct 2018 13:58 - 28 Oct 2018 13:59 #119553
by jsskangas
Replied by jsskangas on topic Following error 6I25 - 7I77
Ok I will try that too.
But 15000mm/min is ok for my home use.
I will try with filter off, then i could get pit more accuracy for machine (increase encoder count pit more).
But 15000mm/min is ok for my home use.
I will try with filter off, then i could get pit more accuracy for machine (increase encoder count pit more).
Last edit: 28 Oct 2018 13:59 by jsskangas.
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