On 06/19/2017 08:51 PM, tom-...@bgp.nu wrote:
Why would I get a following error only while homing (latest Linuxcnc
2.7.9)? I recently added home switches to my machine. My machine
has encoders on the steppers on each of the 3 axes so I want to use
the index pulse for home. I set up the homing sequence each axis
and when I do "Home All" I get a following error on my Z axis (first
one to home). I played with all the settings and can’t get it to
complete unless I set ferror and min_ferror very high Also, once
there is a following error I can only clear it by exiting Linuxcnc
and restarting it. If I just turn it back on, it immediately faults
again with the same following error. If I don’t home, after
restarting Linuxcnc, I can run the Z axis (and X and Y) all day at
any speed without a following error.
I have tried setting the ferror and min_ferror settings to various
reasonable values but it didn’t work. Before adding the switches I
had error=0.001 and min_ferror=0.0005 and never had a following error
appear. I set ferror to 2 and min_ferror to 1 (I think those were
the values) and it worked but then got the following error on the Y
axis (the second axis homed). The values for ferror and min_ferror
that “worked” seem completely unreasonable given I am not even moving
anywhere near my max velocity during homing.
I have tried changing the sign on the HOME_LATCH_VEL to make it
search for index in the other direction but the same thing happens.
Below are my (current) machine hal and ini.
Your ini and hal file look right, except that in the hal file all
stepgens get their .maxvel and .maxaccel from [AXIS_0]. But all your
[AXIS_*]MAXVEL and MAXACCEL have the same value, so it doesn't affect
behavior in any way.
I agree with Jon Elson, the next step in debugging this should be to get
a halscope trace of Z homing and f-erroring, while looking at these pins:
hm2_7i43.0.stepgen.02.position-cmd
hm2_7i43.0.encoder.02.position
hm2_7i43.0.encoder.02.index-enable
axis.2.home-sw-in
Trigger on rising signal on axis.2.f-errored.
--
Sebastian Kuzminsky
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