On Wednesday 10 April 2019 11:28:41 Jon Elson wrote:

> On 04/09/2019 10:16 PM, Gene Heskett wrote:
> > And the interlock needs to know if the loaded code
> > contains an A|B|C move.
>
> OK, now this is going beyond the capabilities of LinuxCNC as
> it is. I think the best way to handle this is to have two
> configs.  If you ever load a G-code file with an A move when
> the config has no A axis, that will generate a fault as soon
> as you LOAD the program. If you really need this protection,
> then two configs is probably the best way.
>
> > Pretty complex... And I'm beat up from yard work, tried to
> > trim a hedge that has some 40mm diameter branches. I'll
> > hurt tomorrow, sure as heck. Humm, maybe I could use a
> > timer trick like I once did in the simulation to generate
> > a dummy home switch. Or a dummy search switch closure
> > thats actually a timedelay, I've done that so code useing
> > a G38.2 could be simulated.
>
> Another way is to use a spare general purpose input that is
> controlled by a jumper in the A axis connector.  Then, when
> no plug (or a shorting plug to keep noise out of the encoder
> inputs) is there, it can be sensed whether the A axis is
> plugged in.  Now, exactly how you use this is a good
> question.  I think you could set up some hal code that will
> cause an error if you run the config with the A axis when it
> is not plugged in.  Or, of course, it could just refuse to
> home A when not present, and that would tell you you have
> loaded the wrong config, or that you need to plug A in and
> rehome.
>
> Jon
>
That idea might be further developed by using the nc contacts, then if 
they aren't closed jog for 1 sec to see if it does close. If not, then 
its not there. But I don't believe LCNC can do that today, and I've no 
clue how much coding it would take to add that. If you knew it was 
clear, one could jog for long enough to tickle the switch, on this one a 
2.5 second jog at search_vel should register a hit. And considering that 
opens a big can of worms, I'm NOT going to campaign for that. So at some 
point when I've nothing better to do, I'll see if I can cobble up a 
halfile list and files that work w/o any great duplication. In the 
meantime I'll muddle along until I paint myself into a corner and must 
have a 3 axis version. The new vfd should be here yet this week, and 
I've more yard work than I want till then.

Cheers Jon, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>



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