Linking two gantry joints with homing switches so it unracks on home

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21 May 2022 17:41 #243497 by dannym
AXIS. That's got me thinking, though. AXIS is pretty dated in appearance. I could add a LinuxCNC profile that uses SilverDragon or whatever. I can already see though that since it defaults to suggesting the last used profile, lots of people are going to just hit "ENTER" and get the SD GUI unintentionally.

Then again, we don't use a lot on the GUI, almost all ops are done with the XHC MPG. And SD's stuff is intuitively labeled and should be familiar enough for users to figure out.

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22 May 2022 00:17 - 22 May 2022 02:04 #243517 by dannym

to prevent jogging before homing change to:
KINEMATICS = trivkins coordinates=XXYZA


OK tried that.  Omitting kinstype=BOTH did not change anything- left/right arrows will drive only joint.0 and rack the machine.
Also of note, the new whole-shop dust collector they put in is deafening- you won't hear the motor stalling, I can see this would be way too easy to push back and forth over and over and actually cause damage with this.

On the other hand, fanning out the XHC jogwheel to jog both joint.0 and joint.4 works just fine!  So, that does mean it will meet the goals to just disable jogging of any joint in joint mode.  

I'm reading through what I can find on AXIS- I see plenty on reconfiguring the appearance of the display, but nothing on changing key function or how the unhomed state works.  Anybody knows if this capability exists and if so where?

The only plan I can think of right now is
hm2_[HOSTMOT2](BOARD).0.stepgen.4.enable pid.4.enable = joint.4.amp-enable-out AND NOT joint.4.homing AND NOT joint.N.homed

But disabling the PID would kill the jogwheel!  I could maybe use joint.4.wheel-jog-active output to enable it, but I'm not clear when that is active.  Since the jogwheel has to use a lowpass filter, so even if it strobes on with a jog command- which seems unlikely- it would miss the lowpass output after the wheel stops.  

Hmm, none of that sounds practical, actually.  Now I'm thinking of a mux, if joint.4 isn't .homing or .homed, then .pid.4.command and .command-deriv are switched to joint.0.motor-pos-cmd  and .vel-cmd otherwise joint.4.motor-pos-cmd
Last edit: 22 May 2022 02:04 by dannym.

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22 May 2022 02:28 #243525 by dannym
Crap, if I somehow fan out joint.0.motor-pos-cmd to both PIDs, then joint.4.motor-pos-fb will get an actual position that it doesn't expect.  Then the joint will have a following error, right?

Man, I'm just not seeing how to fix this.  joint.4 is commanded by AXIS and hardwired it up to the keys this way, there's no way to interrupt it other than to disable the whole joint which would also disable the jogwheel command.  The jogwheel command and jog enable are controllable, but those already work how we want.  



 

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22 May 2022 07:04 #243533 by dannym
At some point the HOME_SEQUENCE got changed back to +2 and not -2, not sure how that happened.

Going back to -2 does lock out all moves, including the coordinated MPG jogwheel, prior to homing.  Really wish we could have retained that coordinated jog but I don't see how.

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22 May 2022 08:55 #243536 by rodw
Somehow,  I see -2 being used a lot. Maybe it is a default in pncconf or stepconf.
From the docs, it should be -1 and that's what I use. The docs indicate -2 is invalid (unless you have two axes with multiple joints)

But as an aside I don't really understand why we have to home a joint axis before it can be jogged. Linuxcnc knows which joints are tied together, why can't a jog request of a single unhomed joint jog its mate?

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22 May 2022 09:26 #243540 by phillc54

From the docs, it should be -1 and that's what I use. The docs indicate -2 is invalid (unless you have two axes with multiple joints)

That not how I read the docs.
"HOME_SEQUENCE = <n> - Used to define the "Home All" sequence. <n> must start at 0 or 1 or -1. Additional sequences may be specified with numbers increasing by 1 (in absolute value). Skipping of sequence numbers is not allowed."

To me this means that so long as your first joint is 0, 1, or -1 then you can increment the number for each joint providing you dont miss a number. The following would be valid:
JOINT0 -2 (X1)
JOINT1 1 (Y)
JOINT2 0 (Z)
JOINT3 -2 (X2)

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22 May 2022 09:45 #243541 by rodw
Yeh, I've read that too. So if your first joint (joint 0)  has a HOME_SEQUENCE of -2 how do the docs allow that when the sequence does not start with 0, 1 or -1? Its very ambiguous.  If you increment a number, -2 is not permitted by my maths.
 

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22 May 2022 09:55 #243543 by rodw

Yeh, I've read that too. So if your first joint (joint 0)  has a HOME_SEQUENCE of -2 how do the docs allow that when the sequence does not start with 0, 1 or -1? Its very ambiguous.  If you increment a number, -2 is not permitted by my maths.

 

What  I mean, if you start with -2, then isn't the sequence -2,-1,0,1,2....
so on one config of mine with YYXZ, I have HOME_SEQUENCE of -1,-1,1,0 which has worked for 5 years and complies with the docs..

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22 May 2022 10:27 #243545 by phillc54
What you have is fine, you could also have -2, -2, 1, 0.
The number indicates the order of homing and the negative sign indicates a synchronous joint. So long as the numbers start at 0 or 1 and the order is consecutive then all is good 

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22 May 2022 12:04 #243549 by rodw

What you have is fine, you could also have -2, -2, 1, 0.
The number indicates the order of homing and the negative sign indicates a synchronous joint. So long as the numbers start at 0 or 1 and the order is consecutive then all is good 

 But that sequence does not start with -1 which by the docs, it must do if it has a joint axis and a 0. This is the confusion I see. -2 is illegal by my read.

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