Odd mesa 5i25 stuttering
- andypugh
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The machine has been running fine for 1 year with linuxcnc and a mesa 5i25 without any adapter board. Because i finally want to mount limit switches, i created a suitable bitfile for the mesa card and also set up the computer fresh.
It seems likely that you changed more than you wanted to change.
What did you change? are you still running the same OS and kernel as was working before, or has your new setup changed these?
What does "uname -a" at the command prompt say?
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- electron
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I did one about a Year ago when I was building the system for the first time. It was not too bad...Looks like there are some relatively huge latency spikes
when LinuxCNC is running. Did you run a latency test?
I've now run one and it is waaay worse... Attached a new plot.
Thanks for that new input! I'll look into these options next!Possible work-arounds if you cannot fix the host latency issues are:
1. Make the maxerror smaller so the maximum velocity modulation
range due to latency is reduced (if you go too small the PID loop will lose
control since it will not have enough range to correct for LinuxCNC <->
5I25 timebase differences)
2. Make a bitfile with the DPLL module and use it to re-time the stepgen
position sampling.
3. Lower the servo thread rate to 500Hz or so
Interestingly it does work great with MDI Commands! Haven't thought about that test yet, thanks! After that I've immediately tested the keyboard if it might output faulty stuff, but it does seem to be okay. (It's also the same one used back then)Are you seeing this while jogging with the keyboard?
As a test try jogging clicking the on screen buttons with a mouse instead of the keyboard keys.
Test using MDI move commands.
Does it still do this when moving with those ways?
What did you change? are you still running the same OS and kernel as was working before, or has your new setup changed these?
What does "uname -a" at the command prompt say?
I was running a Debian 9 (Stretch) install with RT Kernel. I've now switched to Buster + RT Kernel.
Here my current Kernel config:
Linux cnc-pc 4.19.0-11-rt-amd64 #1 SMP PREEMPT RT Debian 4.19.146-1 (2020-09-17) x86_64 GNU/Linux
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- Todd Zuercher
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- tommylight
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- electron
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I've tried a few things mentioned but only got slightly better results. I then comitted to a fresh Install, which fixed all the issues with latency. I really don't know what could have caused this but it might have been a kernel module that I didn't install for my wireless interface this time. Even the new bitfile and configuration made with pncconf are now working as they should.
So, thanks everyone for your help! I got a lot of good input from you and it might help someone else who encounters the latency issues.
Stefan
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