following error while homing only

I noticed that by running homing sometimes a random axis give following error.
after also working for hours no problem.
the system is a closed loop 5i23-7i40 home switch + index.
I do not understand why only while homing ...
regards
Mauro

This can be related to homing to index because of the step in encoder position
when index is detected.

Do you have the per axis index-enable signals connected to the PID
components index enable pin?

this is the hal section of the x axis, however also y and z have the same defect.

#*******************
# AXIS X
#*******************

setp pid.x.Pgain [AXIS_0]P
setp pid.x.Igain [AXIS_0]I
setp pid.x.Dgain [AXIS_0]D
setp pid.x.bias [AXIS_0]BIAS
setp pid.x.FF0 [AXIS_0]FF0
setp pid.x.FF1 [AXIS_0]FF1
setp pid.x.FF2 [AXIS_0]FF2
setp pid.x.deadband [AXIS_0]DEADBAND
setp pid.x.maxoutput [AXIS_0]MAX_OUTPUT
setp pid.x.error-previous-target true

net x-index-enable <=> pid.x.index-enable
net x-enable => pid.x.enable
net x-pos-cmd => pid.x.command
net x-vel-cmd => pid.x.command-deriv
net x-vel-fb => pid.x.feedback-deriv
net x-pos-fb => pid.x.feedback
net x-output => pid.x.output

# ---PWM Generator signals/setup---

setp hm2_5i23.0.pwmgen.01.output-type 1
setp hm2_5i23.0.pwmgen.01.scale [AXIS_0]OUTPUT_SCALE

net x-output => hm2_5i23.0.pwmgen.01.value
net x-pos-cmd axis.0.motor-pos-cmd
net x-enable axis.0.amp-enable-out => hm2_5i23.0.pwmgen.01.enable

# ---Encoder feedback signals/setup---

setp hm2_5i23.0.encoder.01.counter-mode 0
setp hm2_5i23.0.encoder.01.filter 1
setp hm2_5i23.0.encoder.01.index-invert 0
setp hm2_5i23.0.encoder.01.index-mask 0
setp hm2_5i23.0.encoder.01.index-mask-invert 0
setp hm2_5i23.0.encoder.01.scale [AXIS_0]ENCODER_SCALE

net x-pos-fb <= hm2_5i23.0.encoder.01.position
net x-vel-fb <= hm2_5i23.0.encoder.01.velocity
net x-pos-fb => axis.0.motor-pos-fb
net x-index-enable axis.0.index-enable <=> hm2_5i23.0.encoder.01.index-enable
net x-pos-rawcounts <= hm2_5i23.0.encoder.01.rawcounts

# ---setup home / limit switch signals---

net home-x => axis.0.home-sw-in
#net x-home-sw => axis.0.home-sw-in
net x-neg-limit => axis.0.neg-lim-sw-in
net x-pos-limit => axis.0.pos-lim-sw-in

Could you include the entire hal file as an attachment?

OK look normal, what are your following error settings?

There can be a (supposedly small) error spike when index is detected
because the commanded and feedback position have a large step (especially if this is the first home after a startup)

This is patched around in the PID component by using the previous cycles PID output when the index is detected (index-enable falling edge) since the calculated derivatives would be broken in this case. This (one cycle stale PID output) will cause a small glitch especially if index happens during accelerated motion

You might try homing without index to see if the error is still there, and if so
a plot of the following error when homing might shed some light on whats happening.

thanks Pcw
max_ferror = 1 min_ferror = 0.2 I had put them high for the tests.
before using index homing had no problems.
unfortunately this morning it always works and I can not analyze the error ... I will try again calmly.
home search_vel = 5 will not be high I think.

Thanks Tommy
I think the pid is well calibrated because it is perfect at any speed and never goes wrong. seen with halscope never exceeds 5 mv including start and stop at F1000 .. F300 2 mv.
1 mv = 0.001 mm
I feel very good values after I mounted 3600 ppr x 4 14400 cpr encoders
regards
Mauro