Thanks Peter, > From: Peter C. Wallace [mailto:p...@mesanet.com] > On Sat, 12 Sep 2020, John Dammeyer wrote: > > > From: John Dammeyer <jo...@autoartisans.com> > > 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. 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. > > 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
I've also been told that if I see a yellow lightning bolt during boot that the power supply is operating on the edge. And that Pi4's do much better with a 3.5A supply. It's been suggested that I use 12V into a 3A to 4A switching and wire directly to the 5V bus pins rather than go through the power connector. I'm suspecting, but it's not been confirmed, that if the Pi4 thinks the power is marginal that it throttles way back in performance to lower power usage. And that could certainly cause latency issues. I think that's the first place to look. John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
