Hi, I've made good progress converting my little OmioCNC X6 from Mach3
to LinuxCNC. I think I owe a writeup at some point, but I still have a
few glitches before I'm ready to do that.
First thing which I'm worrying about is that having run pncconf, it
generates an output for my open loop steppers which involves a PID type
setup, eg here is my X axis from the ini
[AXIS_X]
MAX_VELOCITY = 100.0
MAX_ACCELERATION = 750.0
MIN_LIMIT = -0.01
MAX_LIMIT = 355.0
[JOINT_0]
TYPE = LINEAR
HOME = 0.0
FERROR = 1.0
MIN_FERROR = 0.01
MAX_VELOCITY = 100.0
MAX_ACCELERATION = 750.0
# The values below should be 25% larger than MAX_VELOCITY and
MAX_ACCELERATION
# If using BACKLASH compensation STEPGEN_MAXACCEL should be 100% larger.
STEPGEN_MAXVEL = 125.00
STEPGEN_MAXACCEL = 937.50
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 10000
DIRHOLD = 10000
STEPLEN = 5000
STEPSPACE = 5000
STEP_SCALE = 320.0
MIN_LIMIT = -0.01
MAX_LIMIT = 355.0
HOME_OFFSET = -5.000000
HOME_SEARCH_VEL = -33.333333
HOME_LATCH_VEL = 0.500000
HOME_FINAL_VEL = 33.333333
HOME_USE_INDEX = NO
HOME_IGNORE_LIMITS = YES
HOME_SEQUENCE = 1
The corresponding .hal (again by pncconf) is as follows:
#*******************
# AXIS X JOINT 0
#*******************
setp pid.x.Pgain [JOINT_0]P
setp pid.x.Igain [JOINT_0]I
setp pid.x.Dgain [JOINT_0]D
setp pid.x.bias [JOINT_0]BIAS
setp pid.x.FF0 [JOINT_0]FF0
setp pid.x.FF1 [JOINT_0]FF1
setp pid.x.FF2 [JOINT_0]FF2
setp pid.x.deadband [JOINT_0]DEADBAND
setp pid.x.maxoutput [JOINT_0]MAX_OUTPUT
setp pid.x.error-previous-target true
setp pid.x.maxerror .0005
net x-index-enable <=> pid.x.index-enable
net x-enable => pid.x.enable
net x-pos-cmd => pid.x.command
net x-pos-fb => pid.x.feedback
net x-output <= pid.x.output
# Step Gen signals/setup
setp hm2_5i25.0.stepgen.00.dirsetup [JOINT_0]DIRSETUP
setp hm2_5i25.0.stepgen.00.dirhold [JOINT_0]DIRHOLD
setp hm2_5i25.0.stepgen.00.steplen [JOINT_0]STEPLEN
setp hm2_5i25.0.stepgen.00.stepspace [JOINT_0]STEPSPACE
setp hm2_5i25.0.stepgen.00.position-scale [JOINT_0]STEP_SCALE
setp hm2_5i25.0.stepgen.00.step_type 0
setp hm2_5i25.0.stepgen.00.control-type 1
setp hm2_5i25.0.stepgen.00.maxaccel [JOINT_0]STEPGEN_MAXACCEL
setp hm2_5i25.0.stepgen.00.maxvel [JOINT_0]STEPGEN_MAXVEL
setp hm2_5i25.0.stepgen.00.step.invert_output true
setp hm2_5i25.0.stepgen.00.direction.invert_output true
# ---closedloop stepper signals---
net x-pos-cmd <= joint.0.motor-pos-cmd
net x-vel-cmd <= joint.0.vel-cmd
net x-output <= hm2_5i25.0.stepgen.00.velocity-cmd
net x-pos-fb <= hm2_5i25.0.stepgen.00.position-fb
net x-pos-fb => joint.0.motor-pos-fb
net x-enable <= joint.0.amp-enable-out
net x-enable => hm2_5i25.0.stepgen.00.enable
# ---setup home / limit switch signals---
net min-home-x => joint.0.home-sw-in
net min-home-x => joint.0.neg-lim-sw-in
net x-pos-limit => joint.0.pos-lim-sw-in
What would someone experienced recommend I do here? This is a simple
openloop stepper machine, no feedback or position sensors. Just a 6i25
to a basic breakout board, going to a chinese 556 stepper driver clone
and onto some small steppers on a 6040 type of machine?
Is there any disadvantage (or advantage) to leaving all the PID and
closed loop stuff in here?
Thanks
Ed W
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