Running HAL commands from python?

Hi
I am working on a custom UI with gscreen. Is it possible to run arbitrary HAL commands from python?

If so, how? Examples?

Thanks!
 

There are some examples using the Hal module and hal_glib module here:
linuxcnc.org/docs/2.8/html/hal/halmodule.html

Thanks for the reply.

I looked this over and I don’t think that “creating a user space component” is what I need to do.

I need to somehow start and stop a realtime thread, among other things. Is this possible?

import os
os.system("halcmd start")

Not super satisfying, but works.

Thank you.

Actually, what I think I want is:
os.system("halcmd -kf")

This appears to work but then it doesn't return and my program is stuck. I can't find an "exit" command for halcmd. Does it have one?
Otherwise, is there a way to send a ctrl-c as part of a script?

Edit: my bad; I was under the impression that I need to provide the -f option to interact with the current instance ...
 

To get out of the halcmd prompt you normally do use "exit"

But I have no idea where you are if you have done that from inside Python.

My mistake was to use the -f option. When I run each line with halcmd, the commands work.

I have another issue now.
When I run the following command:
The command works; it adds the thread. but it causes the hm2 watchdog to time out. 
Is there a good way around this issue? Can I temporarily disable the hm2 watchdog?
It is easy enough to reset the watchdog but then I need to re-home the machine. For this specific use case, re-homing isn't a showstopper but it is not preferable.

More generally, what I am trying to accomplish is to create a cmm using sampler. It is important for this application to set the sample frequency to an arbitrary value, so I want to run it in a separate thread.

Should I abandon this approach and just parse and cull the sampler output instead?  



 

Do you really want a 1 second thread? That seems to be more than the usual number of zeros.

No, I fat-fingered a few too many in there. The actual period is calculated from scan speed and point interval specified by the user.

There is, I think, some sort of limitation that threads have to be added in order, though I am not sure i it is slow to fast or vice-versa.

I would try experimenting in a bare halcmd prompt and see what happens.


ie, see what you are allowed to do without the rest o LinuxCNC interfering.