method for resting a stepgen position to zero?

Been trying to find a way to seting the position of a stepgen to zero

one way would be to unlink the output then use a position-cmd to zero
then reconnect it. Not a very elegant solution

Is there a better way?

The goal is to reliably position the spindle for a tool change.
The 5i25 & 7i76 board combo provides ten stepgens in this case
spindle step/dir & encoder is provided Via the 7i76 TB3 stepgen.04

I have explored several possible methods to achieve orienting the
spindle.

The best idea I have so far works like this:
Use a M100 type G code containing an executable written with C and
Hal commands.

Set stepgen.04.control-type to FALSE (position control mode)
Read the stepgen.04.counts Sum this with a constant which equates to
2 turns of the spindel. Set the encoder.00.latch-enable to TRUE.
Read stepgen.04.maxval and save it to a temp var.
write stepgen.04.maxval a constant which equates to 60 RPM
Write to stepgen.04.position-cmd the new postion sum.

On encoder.00.latch-enable FALSE Read the stepgen.04.counts Sum this
with a constant (relative to the index) tool change position for the spindle.
rewrite to stepgen.04.position-cmd the new position sum.

Hopefully the spindle stops at the desired tool change position

write stepgen.04.maxvel temp var
Set stepgen.04.control-type to TRUE (velocity control mode)
Exit

In Hal Configuration I have manually tested changing the stepgen.04.control-type,
stepgen.04.maxvel and imputing positions to stepgen.04.position-cmd and the
encoder.00.index-enable which is bi directional pin connected to a signal.
In order to test had to unlink it.

I am uncertain how to deal with bi directional pins and signals in Hal
and if there is a way to mux the encoder.00.index-enable pin so runtime
unlinking and re netting would be unnecessary.

Despite it's appearance This seem the cleanest way to do it.
Unfortunately I have no experience building a M100 executable and
combining C with Hal commands I am assuming this can be done.

Excellent ! I assume that a multiplexor is used such that

When Then when motion.spindle-orient = TRUE connect pins
orient.0.comand to stepgen.04.velocity-cmd.

When Then when motion.spindle-orient = FALSE connect pins
spindel-vel-cmd-rps to stepgen.04.velocity-cmd.

Is this correct?

The spindle is a self contained DC servo drive which accepts
step & dir like a step motor.

Thanks again guys

Here is my custom Hal code making use of orient.
There must be error some where since it fails to function.

loadrt mux2 count=1
loadrt orient count=1

addf orient.0 servo-thread
addf mux2.0 servo-thread

unlinkp hm2_5i25.0.stepgen.04.velocity-cmd
net orient-sig-out orient.0.command => mux2.0.in1
net spindle-vel-cmd-rps => mux2.0.in0
net mux2-select-sig motion.spindle-orient => mux2.0.sel => orient.0.enable
net mux2-output-sig mux2.0.out => hm2_5i25.0.stepgen.04.velocity-cmd

I missed seeing the pid part.

I have muddled my way through the coding of the ORIENT and it WORKS!!!!!

How ever the doc example has some flaws

The example [net spindle-pos ...encoder..position orient.position orient-pid.position] is confusing

The Pin [orient-pid.position] dose not exist, actually it should be [orient-pid.feedback]

My line of code ended up like this [net spindle-revs orient.position orient-pid.feedback]

Other wise the between the Docs and the man pages I made it through the process.

Again thanks for the helping hand