Hello Everybody,
many thanks for your great input. It has given me some ideas of what I
can try next.
As we have a holiday on Monday I will not be in the shop until Tuesday.
I have a ssh connection to the machine, but since I started this thread
the machine has been running linuxcnc with the 7i43+7i33+interface pcb
without any problems in the lab again. The current load of the machine (
uptime/top ) is about 6, and I still have a working realtime for almost
two days now.
Summarizing all replies, ideas, questions.
1. Ntp/network is a good idea, since I do have this setup via cron to
check the time every 20 minutes. However, these ntp updates happen also
in the lab, and there I don't get any watchdog bite. Anyway I'll disable
the ntp updates and see what happens.
2. Yes, I should have saved the output of dmesg. I checked it, but did
not save it. There was no "unexpected realtime delay" message, that I do
remember. I will save dmesg's output next time.
3. I am running a 1ms servo loop on two other linuxcnc machines with
7i43+7i33. A 1ms servo loop only works for me with onboard lpt ports. I
had no such luck with pci boards. I must say that I have never checked
with pci-e cards. When building a pc for use with linuxcnc I just always
make sure to have an onboard lpt port for the epp communication. This a
dual core machine at 3GHz that I am using, so there is enough cpu power
to spare, even if one core is busy with the servo loop.
And after Friday's email to the list, the last thing I tried was running
with a 5ms servo loop and the watchdog did bite again.
4. Monitoring the epp communication with a digital scope would be an
option, I don't have one myself, but I know somebody how does. Certainly
it would make sense to see if the communication really breaks down for
over 500ms. But I know nobody who owns a logic analyzer, so I can only
check 2 chan max. What pins on the ribbon cable are the most interesting ?
5. EMI certainly/unfortunately is a possibility. The ribbon cable from
the pc to the 7i43 is short, about 30cm, but who knows what kind of EMI
I do have in a 30y old mill. And of course the ribbon cable is not
shieled either. I tried running with the converter for the spindle
powered down, but that did not help either.
6. The 7i43's watchdog timeout I first had set to 5ms, then 100ms and
increased that value to a final value of 500ms. And still I got watchdog
bites at a timeout of 500ms without any unexpected realtime delay
message. Of course, once the watchdog bites, I get following errors too
since the axes don't move anymore once the watchdog has bitten.
7. I will try to decrease vm swappiness from 60 (ubuntu's default) to
10. The machine has 4Gb ram of which only 3,5 are useable because of the
32bit architecture. The linuxcnc pc never runs anything except linuxcnc,
so it should never swap anyway.
8. External events. I could use the 7i43's hm2_7i43.0.watchdog.has_bit
pin as a trigger for halscope, but what other events should I monitor in
halscope ? Halscope can only monitor a maximum of 8 channel, I believe.
Or does somebody have an working example of a streamer/halstreamer setup
that I could copy. Anyway, what other values from hal space would be
interesting to debug this ? Ferror, cmd pos, fb pos, velocities, accel
for all axes, pwm values, the watchdog has-bit pin, the io_error pin,
and what else ?
9. Question. Since I don't have an io_error
16 bit RW FALSE hm2_7i43.0.io_error
and the documentation at
http://linuxcnc.org/docs/html/man/man9/hm2_7i43.9.html tells me that the
io_error should be set if I do have a broken epp communication, does
that mean that I can rule out EMI on the cable from the lpt port to the
7i43 ?
10. I could buy a pcie lpt port and see if that helps.
11. Video drivers are vesa, no nvidia hardware. No flash, no firefox,
nothing but the linuxcnc ubuntu 10.04 32bits and the cnc software running.
12. Did I forget something else that I could check ?
BR
Max.
> On Fri, 17 May 2013, Sebastian Kuzminsky wrote:
>
>> Date: Fri, 17 May 2013 15:33:05 -0400
>> From: Sebastian Kuzminsky <[email protected]>
>> To: "Enhanced Machine Controller (EMC)" <[email protected]>
>> Subject: Re: [Emc-users] 7i43 watchdog has bitten, looking for the cause ?
>>
>> On 05/17/2013 03:27 PM, Andrew wrote:
>>> 2013/5/17 Maximilian H <[email protected]>
>>>
>>>> I use a
>>>> servo loop of one millisecond.
>>>>
>>>
>>> I'd say 1ms is too short for 7i43, at least it never worked for me. Try
>>> increasing it to 4ms to eliminate the possible cause.
>>
>> I've run a 7i43 at 1 kHz, "it worked fine for me". I guess it would
>> depend on the user's hardware how well it works.
>>
>> Maximilian reported that after a watchdog bit, the max time taken by the
>> servo thread was 765 us:
>>
>>> Realtime Threads:
>>> Period FP Name ( Time, Max-Time )
>>> 498550 YES servo-thread ( 6060, 764883 )
>>
>> ... so a 1 ms servo period doesn't seem to be the problem here.
>>
>>
>> --
>> Sebastian Kuzminsky
>
>
>
> Another possibility that Sebastian hinted at is that there's an electrical
> noise problem. This could cause a false reading that indicates a watchdog
> timeout even though one has not happened (though you would expect many
> readings to be corrupted in this case not just watchdog state)
>
>
> Peter Wallace
> Mesa Electronics
>
> (\__/)
> (='.'=) This is Bunny. Copy and paste bunny into your
> (")_(") signature to help him gain world domination.
>
>
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