Adding Minmax to Axis

This is more of an Axis question but since I'm using PNCConf to configure......

Each time I attempt to run Axis I get a joint 2 following error and instead of fixing the issue I thought it would be nice to measure it.
BTW, I'm a bit surprised that a following error occurs at all considering there is no hardware being driven and thus there is zero inertia.
Anyway I added the following to custom.hal:

loadrt minmax count=3

addf minmax.0 servo-thread
addf minmax.1 servo-thread
addf minmax.2 servo-thread

net axis.0.ferror minmax.0.in
net axis.1.ferror minmax.1.in
net axis.2.ferror minmax.2.in

Run Axis - Machine/Show Hal Config/Pins/minmax show the pins but even under WATCH their value remains unchanged after running Axis (which then stops with the following error.

I'm not sure what Minmax is supposed to measure (time, volts, etc).
I can't find much about it on LinuxCNC,
Any ideas on how to make Minmax work?

Hi

I have not used it myself, but running man minmax brings up the scant info, which shows it is for measuring floating point values

Your problem may be that you do not have a signal in your net commands, you are trying to link 2 pins, but net links a signal to one or more pins, so it will see the first argument as a signal name.

Try net Xferror axis.0.ferror minmax.0.in or similar

regards

thanks arcEye, what is X? I'm new to this.

That is simply my assumption that axis.0 is going to be the X axis!

You can call the signal anything you want as long as that name is not already in use as a signal or pin

regards

"BTW, I'm a bit surprised that a following error occurs at all considering there is no hardware being driven and thus there is zero inertia."

With a servo system you will get a joint following error anytime the feedback (encoder usually) and commanded position differ by more than the current ferror limit.

This means that if no hardware is connected you will get an immediate joint following error
as soon as you try to move (commanded position changes but the encoder count does not follow)

thanks ArcEye I'll play with it tomorrow.

PCW wrote:

"BTW, I'm a bit surprised that a following error occurs at all considering there is no hardware being driven and thus there is zero inertia."

With a servo system you will get a joint following error anytime the feedback (encoder usually) and commanded position differ by more than the current ferror limit.

This means that if no hardware is connected you will get an immediate joint following error
as soon as you try to move (commanded position changes but the encoder count does not follow)

OK, catch XX.
So what is the solution?
Delete the encoders?

Not sure what you are trying to do here. If you just wish to avoid following errors when tuning and messing about, I would set min-ferror and ferror to around 1 inch (or 25 mm) so the servo behavior is observable but a runaway is stopped before it gets too far.

simple basic servo setup:

1. With drives disabled, verify proper encoder counting, direction and scale for all axis

2. Next check (and possibly correct) feedback direction.
There are many ways to do this and perhaps pncconf can help

3. Once feedback direction is correct, and with working drive enable circuitry,
you proceed to tuning

PCW, thanks, I'm just messing around with Axis and PNCConf with no hardware attached. I completely overlooked that encoder input would be expected. I will use your suggestion when I get to the hardware.
For now I would just like to get Minmax working in Axis. I need to read up on signal
and pin connections.

ArcEye wrote:

That is simply my assumption that axis.0 is going to be the X axis!

You can call the signal anything you want as long as that name is not already in use as a signal or pin

regards

OK, thanks, I got it.
Also thanks to =aike= on CNCZone (message117480)

This works in the custom.hal file.

loadrt minmax count=3

addf minmax.0 servo-thread
addf minmax.1 servo-thread
addf minmax.2 servo-thread

net Xferror axis.0.f-error minmax.0.in
net Yferror axis.1.f-error minmax.1.in
net Zferror axis.2.f-error minmax.2.in



In order to get the Axis cutter path example to work, in the .ini file both MIN_FERROR and FERROR need to be set at a bit more than the G code max numbers.