Homing the Spindle

REEEN wrote:

How can I force spindle homing like axis homing before running any commands or programmes ?

To home the spindle you need to set the spindle encoder index-enable pin high, then rotate the spindle past the index.

There are a number of ways that this could be done, but none currently exist as a built-in part of LinuxCNC. I have raised a feature request
sourceforge.net/p/emc/feature-requests/138/

I need to experiment when at a machine, but it is possible that a G33 command in startup G-codes might have the desired effect.
Or, potentially, linking a G33 as an MDI_COMMAND to the X-axis is-homing pin.

[quote="REEEN" post=62041I managed to solve the problem with a remap procedure and some mcodes running bash scripts.
...
Connecting a homing axis with a mdi command is not possible because mdi commands cannot be run before axis are homed[/quote]

Ah, yes, that does complicate matters.

<thinking aloud>
You can "sets" the spindle-index-enable in the HAL file.
If the position-control loop was arranged to output a fixed spindle speed if the index-enable was still set when position mode was enabled, then the spindle would first move through index before aligning itself.
This could be done with a mux2, I _think_ that the mux2.N.sel pin can be connected to the index-enable signal, but I am not 100% sure.
One would have to be careful to consider the case in a specific HAL file where the spindle was in velocity mode for rigid tapping (as an example) where the index-enable pin goes high before the start of the move.
In the typical setup:





You could replace the circled Mux2 with a Mux4, and connect position-mode-and-index-enable-set to a fixed speed, position-mode-and-not-index-enable to the position pid, and the other two inputs to the velocity pid.



If you are using Master then you might like to note that there are new pins in the orient component to drive the motion.spindle-is-oriented inputs:
orient.N.is-oriented bit out orient.N.tolerance float in www.linuxcnc.org/docs/devel/html/man/man9/orient.9.html
I possibly should have added them in 2.7, but didn't. You could halcompile --install the Master version if you wanted to.

REEEN wrote:

But I prefer my way with remapping and bash scripts, it was less work.

I think that the HAL way is less work if you are doing it as part of the HAL setup, rather than adding it later.
Basically all that changes is that the mux2 that chooses between the PID outputs becomes a mux4.

NitroCH3NO2 wrote:

How did you generate the HAL diagram in the above post?

By hand. I did it some time ago for the Wiki.

The component tables were copy-pasted from halcmd to Excel, then formatted and aligned there, and copied to Inkscape where the arrows were added.