Dead in the water on 7i92 config

What's the practical difference between velocity mode and position mode?

In position mode Linuxcnc just sends a position command to a servo drive, or the step generator component, and there is no real need for feed back this is considered "open loop" (more of a one way line). In velocity mode Linuxcnc just sends a velocity command to a servo drive or the step generator and they must feed back the position to Linuxcnc where the position loop is "closed " a PID loop is used to determine the velocity command that is sent to the drive or stepgen.

The PID system allows more control parameters that create a more robust
control loop when there is jitter cause by the host Ethernet connection

So it is suggested to not use the built in driver position mode which is not robust WRT host jitter
for Ethernet connected devices

I sat down with it again tonight but couldn't figure out ' "wire" the gantry.0.joint.00.pos-cmd into the system'.

So the new lines are
net x0pos-cmd gantry.0.joint.00.pos-cmd => hm2_[HOSTMOT2](BOARD).stepgen.00.position-cmd
net x0pos-fb gantry.0.joint.00.pos-fb <= hm2_[HOSTMOT2](BOARD).stepgen.00.position-fb
net x1pos-cmd gantry.0.joint.03.pos-cmd => hm2_[HOSTMOT2](BOARD).stepgen.03.position-cmd
net x1pos-fb gantry.0.joint.03.pos-fb <= hm2_[HOSTMOT2](BOARD).stepgen.03.position-fb
net xpos-cmd gantry.0.position-cmd <= axis.0.motor-pos-cmd
net xpos-fb gantry.0.position-fb => axis.0.motor-pos-fb
net xenable axis.0.amp-enable-out => hm2_[HOSTMOT2](BOARD).stepgen.03.enable hm2_[HOSTMOT2](BOARD).stepgen.03.enable


The existing lines::
net emcmot.00.pos-cmd axis.0.motor-pos-cmd => pid.0.command
net emcmot.00.vel-cmd axis.0.joint-vel-cmd => pid.0.command-deriv
net motor.00.pos-fb <= hm2_[HOSTMOT2](BOARD).0.stepgen.00.position-fb axis.0.motor-pos-fb pid.0.feedback
net motor.00.command pid.0.output hm2_[HOSTMOT2](BOARD).0.stepgen.00.velocity-cmd
setp pid.0.error-previous-target true

Not well enough, apparently.

here's the main part of the change ( connecting the gantry comps position command outputs to the PID command inputs)

net x0pos-cmd gantry.0.joint.00.pos-cmd => pid.0.command
net x0pos-fb gantry.0.joint.00.pos-fb <= hm2_[HOSTMOT2](BOARD).stepgen.00.position-fb
net x1pos-cmd gantry.0.joint.03.pos-cmd => pid.3.command
net x1pos-fb gantry.0.joint.03.pos-fb <= hm2_[HOSTMOT2](BOARD).stepgen.03.position-fb
net xpos-cmd gantry.0.position-cmd <= axis.0.motor-pos-cmd
net xpos-fb gantry.0.position-fb => axis.0.motor-pos-fb
net xenable axis.0.amp-enable-out => hm2_[HOSTMOT2](BOARD).stepgen.00.enable hm2_[HOSTMOT2](BOARD).stepgen.03.enable

setp pid.0.error-previous-target true
setp pid.3.error-previous-target true

note that PID command deriv connections on the gantry driven axis must be disconnected
since the commands are no longer coming from emcmot

# net emcmot.00.vel-cmd axis.0.joint-vel-cmd => pid.0.command-deriv
This doesn't cause much harm, as the PID component generates it own command derivative if the pin is not connected

OK I'm trying- I'm unclear on whether ONLY the bold lines are to be used, or all of them?

With ONLY the bold lines, I get:
Pin 'gantry.0.joint.03.pos-cmd' does not exist

With all the lines included, I get:
Pin 'hm2_7i92.stepgen.00.position-fb' does not exist

My X[0]-drive section is:
newsig emcmot.00.enable bit
sets emcmot.00.enable FALSE

net emcmot.00.enable <= axis.0.amp-enable-out
net emcmot.00.enable => hm2_[HOSTMOT2](BOARD).0.stepgen.00.enable pid.0.enable


# position command and feedback
net emcmot.00.pos-cmd axis.0.motor-pos-cmd => pid.0.command
net emcmot.00.vel-cmd axis.0.joint-vel-cmd => pid.0.command-deriv
net motor.00.pos-fb <= hm2_[HOSTMOT2](BOARD).0.stepgen.00.position-fb axis.0.motor-pos-fb pid.0.feedback
net motor.00.command pid.0.output hm2_[HOSTMOT2](BOARD).0.stepgen.00.velocity-cmd
setp pid.0.error-previous-target true


# timing parameters
setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.dirsetup [AXIS_0]DIRSETUP
setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.dirhold [AXIS_0]DIRHOLD

setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.steplen [AXIS_0]STEPLEN
setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.stepspace [AXIS_0]STEPSPACE

setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.position-scale [AXIS_0]SCALE

setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.maxvel [AXIS_0]STEPGEN_MAX_VEL
setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.maxaccel [AXIS_0]STEPGEN_MAX_ACC

setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.step_type 0
setp hm2_[HOSTMOT2](BOARD).0.stepgen.00.control-type 1

# set PID loop gains from inifile
setp pid.0.Pgain [AXIS_0]P
setp pid.0.Igain [AXIS_0]I
setp pid.0.Dgain [AXIS_0]D
setp pid.0.bias [AXIS_0]BIAS
setp pid.0.FF0 [AXIS_0]FF0
setp pid.0.FF1 [AXIS_0]FF1
setp pid.0.FF2 [AXIS_0]FF2
setp pid.0.deadband [AXIS_0]DEADBAND
setp pid.0.maxoutput [AXIS_0]MAX_OUTPUT
setp pid.0.maxerror [AXIS_0]MAX_ERROR

The original sample code that i copy pasted from a previous reply
had some errors (missing board numbers mainly)
also the gantry comp will just have 2 axis by default, 00 and 01


This should be closer:


net x0pos-cmd gantry.0.joint.00.pos-cmd => pid.0.command
net x0pos-fb gantry.0.joint.00.pos-fb <= hm2_[HOSTMOT2](BOARD).0.stepgen.00.position-fb
net x1pos-cmd gantry.0.joint.01.pos-cmd => pid.3.command
net x1pos-fb gantry.0.joint.01.pos-fb <= hm2_[HOSTMOT2](BOARD).0.stepgen.03.position-fb
net xpos-cmd gantry.0.position-cmd <= axis.0.motor-pos-cmd
net xpos-fb gantry.0.position-fb => axis.0.motor-pos-fb
net xenable axis.0.amp-enable-out => hm2_[HOSTMOT2](BOARD).0.stepgen.00.enable hm2_[HOSTMOT2](BOARD).0,stepgen.03.enable

setp pid.0.error-previous-target true
setp pid.3.error-previous-target true

The bolded lines were lines I added to the previous reply

Do read the gantry comp manual page, you will need to feed the
limit switch data through the gantry comp, just as you feed
motions X axis position commands through the gantry comp to
to split it into two motion commands that allow independent motion for homing