Creating custom HAL pin in QtPyVCP

I'm trying to create a hal pin that indicates the current coordinate system. This pin does not exist in HALUI. There was some discussion of the creation of this pin here:
forum.linuxcnc.org/24-hal-components/454...or-coordinate-system
'If you converted it to one of the others then I think that the Python handler code could poll the linuxcnc.status() and update itself.'
(The value to retrieve is g5x_index.)

This link explains how to use the Python Interface:
linuxcnc.org/docs/2.7/html/config/python...ding_linuxcnc_status

This link explains how to use GStat to create a custom HAL pin:
linuxcnc.org/docs/html/gui/GStat.html#_sample_gstat_code

I was wondering if I chose to go down this route whether this is the simplest way to do this in QtPyVCP?, or am I missing something and there is a better way? Is there anything else that I should be aware of?

The purpose of this hal pin is create a message whenever the coordinate system is changed in auto mode, primarily used to indicate when M5 or M30 change the coordinate system. I recently destroyed a touch probe by accidentally ending a handwritten probing routine with M30, causing me to accidentally run the program in wrong coordinate system the second time, and rapid the probe into a fixture.

Any help is much appreciated!

You mention GStat...
Are you using QtVCP which is part of LinuxCNC, or QtPyVCP which is a separate project?

If using QtPyVCP it should be easy to add such a HAL pin using the HAL interface and the LinuxCNC status plugin.

Connect a handler to the status.g5x_index datachannel and set the HAL pin the value passed to the handler.

www.qtpyvcp.com/hal.html
www.qtpyvcp.com/designer/plugins/status.html

I'll see if I can provide an example.

This is the code you would add to your VCP mainwindow.py file to add the HAL pin


 

Thanks so much for the help! Somehow managed to not spot www.qtpyvcp.com/hal.html.

I'm using probe_basic, so I've added your example to my probe_basic.py. 
            
I still can't see the qtpyvcp.g5x_index pin under Hal Show, and I can't add it to a signal in my custom_postgui.hal file. Have I missed anything?

Solved, the issue was with indentation, and using tabs instead of spaces. The following worked!

Thank you, this should be very useful!

I've got a bit more work to do as g5x_index currently initialises with a value of 0 (indicating G53) and it would be preferable if it initialised with a value indicating the active work coordinate system (which is persistent across restarts in my case). This means that initialising with the stored value could be an option (although there may be simpler ways).
 

Glad it worked!

You can initialize the HAL pin value like this:
This should work if placed at the end of your __init__ method.