Dead in the water on 7i92 config
13 Feb 2016 18:42 #70080
by dannym
Replied by dannym on topic Dead in the water on 7i92 config
How do I plot following error?
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13 Feb 2016 18:48 #70081
by PCW
Replied by PCW on topic Dead in the water on 7i92 config
With halscope, plotting axis.N.f-error (N being the axis of interest)
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14 Feb 2016 02:00 #70092
by dannym
Replied by dannym on topic Dead in the water on 7i92 config
Well, I was searching through the docs on .ini again-
I used the values in the 7i92step.zip file given earlier:
FERROR = .0002
MIN_FERROR = .0001
This is substantially different than the linuxcnc ini doc defaults:
MIN_FERROR = 0.010
FERROR = 1.0
I don't really understand what the meaning of what the number is. Yes I have the manual at linuxcnc.org/docs/2.6/html/config/ini_config.html , but I don't get what an "error" is without encoder feedback, or a perspective on what number is appropriate.
Well setting FERROR=1 & MIN_FERROR=0.010 made the Following Errors disappear. But I don't know if that's a fix or just a hack masking something else?
I used the values in the 7i92step.zip file given earlier:
FERROR = .0002
MIN_FERROR = .0001
This is substantially different than the linuxcnc ini doc defaults:
MIN_FERROR = 0.010
FERROR = 1.0
I don't really understand what the meaning of what the number is. Yes I have the manual at linuxcnc.org/docs/2.6/html/config/ini_config.html , but I don't get what an "error" is without encoder feedback, or a perspective on what number is appropriate.
Well setting FERROR=1 & MIN_FERROR=0.010 made the Following Errors disappear. But I don't know if that's a fix or just a hack masking something else?
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14 Feb 2016 11:58 #70104
by BigJohnT
Replied by BigJohnT on topic Dead in the water on 7i92 config
A good read here linuxcnc.org/docs/2.7/html/config/steppe...html#_error_messages
You should be reading the current docs not the 2.6 docs unless your using 2.6.
JT
You should be reading the current docs not the 2.6 docs unless your using 2.6.
JT
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14 Feb 2016 17:58 - 14 Feb 2016 17:59 #70126
by PCW
Replied by PCW on topic Dead in the water on 7i92 config
You can certainly set the following error limits so wide that it's impossible to ever get a following error.
This will definitely mask many types of setup issues
You can also set the limits so tight that you get following errors caused by
real time jitter in the hosts position sampling time. (this is much improved if the DPLL is used)
The ideal values are ones that are small enough to detect errors that compromise your machine tolerance
but large enough that you do not get nuisance following error trips
Note that the limits in the example file should be OK, here is a plot of X following error with a fairly well tuned system:
freeby.mesanet.com/1khzstepgen.png
Note the the scale for the following error is 5 uinch/division so peak following error is about 2 uinch
this is a 480 IPM 80 IPS^ setup with a 1 KHz servo thread
This is why I suggested plotting the error, and posting your hal/ini files so I or others on the forum can possibly spot setup issues.
This will definitely mask many types of setup issues
You can also set the limits so tight that you get following errors caused by
real time jitter in the hosts position sampling time. (this is much improved if the DPLL is used)
The ideal values are ones that are small enough to detect errors that compromise your machine tolerance
but large enough that you do not get nuisance following error trips
Note that the limits in the example file should be OK, here is a plot of X following error with a fairly well tuned system:
freeby.mesanet.com/1khzstepgen.png
Note the the scale for the following error is 5 uinch/division so peak following error is about 2 uinch
this is a 480 IPM 80 IPS^ setup with a 1 KHz servo thread
This is why I suggested plotting the error, and posting your hal/ini files so I or others on the forum can possibly spot setup issues.
Last edit: 14 Feb 2016 17:59 by PCW.
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15 Feb 2016 00:11 #70137
by dannym
Replied by dannym on topic Dead in the water on 7i92 config
Well, here it is- FERROR peaks at about 0.07.
Axis 3 is sync'ed to Axis 0 (X)
I was still getting Following Error on Joint 0 sometimes when switching from Jog Mode to MDI. When it did that, it could NOT be reset. Toggle EStop/Toggle Machine Power would only repeat the Following Error and no motion as soon as a move was commanded. I had to quit LinuxCNC and restart it.
Axis 3 is sync'ed to Axis 0 (X)
I was still getting Following Error on Joint 0 sometimes when switching from Jog Mode to MDI. When it did that, it could NOT be reset. Toggle EStop/Toggle Machine Power would only repeat the Following Error and no motion as soon as a move was commanded. I had to quit LinuxCNC and restart it.
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15 Feb 2016 00:26 #70138
by PCW
Replied by PCW on topic Dead in the water on 7i92 config
Can't really tell but sort of looks like a real time error or Ethernet hardware problem to me
Can you tell me what OS (the result of uname -a), Ethernet hardware
and LinuxCNC version you are running?
Have you run a latency-test or latency-histogram? what were the results?
Can you tell me what OS (the result of uname -a), Ethernet hardware
and LinuxCNC version you are running?
Have you run a latency-test or latency-histogram? what were the results?
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15 Feb 2016 06:43 #70151
by dannym
Replied by dannym on topic Dead in the water on 7i92 config
Ah it's looking pretty large, in the 14,000,000 territory. I also went through and found that it's an Intel 82801 chipset- which is known to cause problems because of its system interrupts.
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15 Feb 2016 17:12 #70169
by PCW
Replied by PCW on topic Dead in the water on 7i92 config
Are you sure you are running a Preempt-RT kernel?
Frequent multi-ms latencies sounds more like a non-RTOS kernel to me
Frequent multi-ms latencies sounds more like a non-RTOS kernel to me
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16 Feb 2016 01:01 #70206
by dannym
Replied by dannym on topic Dead in the water on 7i92 config
uname -a
linux localhost 3.4-9-rtai-686-pae #1 smp PREEMPT Debian 3.4.55-4 linuxcnc i686 Gnu/Linux
linux localhost 3.4-9-rtai-686-pae #1 smp PREEMPT Debian 3.4.55-4 linuxcnc i686 Gnu/Linux
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