> From: Peter C. Wallace [mailto:p...@mesanet.com] > On Wed, 3 Mar 2021, John Dammeyer wrote: > > > Date: Wed, 3 Mar 2021 23:11:23 -0800 > > From: John Dammeyer <jo...@autoartisans.com> > >>> The comment on the link about Ethernet latency is what interested me. > >>> Again if electrical noise causes retries or delays in the Ethernet > >>> signalling then that could cause this sort of error under heavy load. > >>> > >>> John > > Hi Gene, My AC Servo is run open loop with step/dir. It's not the Servo > > Driver that is calling out a following error. It's LinuxCNC that also has > > no > > clue where the motor actually is unless the AC servo asserts a fault output. > > And it can't do that because I disconnected it for this test. > > > > I don't know how the Ethernet Communications with the MESA 7i92H works. > > Page > > 8 of the user manual says it's UDP which means launch and forget. The > > sender > > has no way of knowing if the message was received although with only two > > devices perhaps there's a lower level that does verify that. > > > > In either case Page 31 states there are error counters so if there is a > > packet > > error that is detected after a new motion command is issued; like change > > direction for example. Then LinuxCNC might well decide to throw up a > > following error. > > > > I will admit that I misread the HAL instructions and had the > > MAX_ACCELERATION > > parameter set to 125% higher. But with Backlash it was supposed to be 200%. > > Once I changed that the problem went away. So bad HAL info generates a > > following error? Except that never happened without the extra 92 lbs on the > > table. > > A following error is _expected_ if the stepgen maxaccel parameter is not at > least 2x the joints maxaccel value (or if any stepgen constraint is lower > than what linuxCNC may command it to do) So HAL setup can absolutely cause > following errors. Should not the HAL driver code flag that error on start up? Ie. Pseudo code IF (BACKLASH <> 0.0) AND (STEPGEN_MAXACCEL < (MAX_ACCLERATION *2) THEN ERROR in Parameter STEPGEN_MAXACCEL.
> > > > But if electrical noise from the higher load did cause a damaged UDP packet > > then there's the answer. A quick change in direction to handle backlash > > and a > > missing message throws out the timing and results in a following error. John > > You can check this by plotting hm2_7i92.packet-error , but if setting the > stepgen maxaccel value stops the following errors it does not seem likely they > are caused by lost packets. Plotting the following error will also give you > some > insight into whats going on. > Peter Wallace > Mesa Electronics I'll try that but it doesn't explain why there were no following errors without the extra 92 lbs on the table and the incorrect STEPGEN_MAXACCEL. I believe the Following Error Joint 2 message is incorrect. Perhaps you can explain why that message shows up at all in an open loop situation? What does the FPGA do that would cause that? Is there a separate message for missing Ethernet or out of sequence Ethernet packets or is it lumped into Following Error on Joint? Thanks John _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
