On Sat, 12 Sep 2020, John Dammeyer wrote:
Date: Sat, 12 Sep 2020 19:13:43 -0700
From: John Dammeyer <jo...@autoartisans.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "'Enhanced Machine Controller (EMC)'" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Mini-PC
Mini USB cable arrived via Amazon today so I could power the HDMI to VGA
dongle. After that it was quick work to move cables from the PC and monitor to
the Pi4. cid:image002.jpg@01D68936.9A816960 USB uses mouse, keyboard and power
for the dongle. A 5V,2A wall wort for the Pi4. The Ethernet cable goes to
the to the Mesa 7i92H down in the cabinet and it's powered from the system
power supply.
I had loaded the new LinuxCNC Pi distribution a couple of times a few days
ago. Second time lucky and it finally worked with the 7i92H. I had also
moved over the HAL and INI files from my PC version LinuxCNC.
Deep breath. Switch on Master Power. Wait for it to boot and then click on
the desktop icon for the mill. Why is it that these short cuts throw up that
stupid dialog asking if I want to run it directly or in a terminal window.
Why isn't there checkbox that says yes always?
Anyway. LinuxCNC booted. I clicked on the ON button. Tried the spindle.
Worked. Homed everything. That worked. Then suddenly it complains that the
task with 1000000 is too slow and it will only tell me that once.
Ran a few G-Code samples. Ethernet connection reported once that a read to
the 7i92H had failed. Had to stop and restart LinuxCNC since that also took
out the master relay. No reboot needed though.
Ran some more G-Code. Tried the G01 G93 X1 A60 F0.707. Worked fine.
So other than latency warnings and unreliable Ethernet communications it could
be used to run the mill. But I wouldn't trust it.
Now this could be a power supply or grounding issue. I think mounting the Pi
in a proper metal box, adding a heatsink or even a fan and using a power
supply with more than 2A capability would go a long way to getting rid of
spurious issues. It's even possible that the latency issue is due to the
translation to VGA from HDMI but I always thought that the latency issue was
not a problem with Ethernet based Mesa boards.
cid:image006.jpg@01D68936.9A816960
John Dammeyer
Latency is less of an issue since LinuxCNC is not doing very high
speed things, but you still to run the servo thread reliably.
The read error means that a read request timed out 5 times in a row
(default timeout is 80% of the servo thread period)
You might try 2 ms servo thread. Others have needed that on a
RPI4
Peter Wallace
Mesa Electronics
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