motmod unlock_joints_mask not working

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24 Apr 2021 11:47 #206945 by mwinterm
Hello,

I have a machine which can lock the z-axis (joint2). To get the corresponding hal-pins I added to the motmod line
unlock_joints_mask=0x20

(00100000 = 0x20)

LinuxCNC starts as normally, no error but I still do not have the unlock and the is-unlocked pin available for joint 2.

I'm using LinuxCNC 2.8.1

Any help welcomed...

Best regards,

Marc

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24 Apr 2021 12:03 #206946 by mwinterm
I could somehow solve the problem by setting
unlock_joints_mask=4

But have no idea why this has to be 4. Does not correspond to the LSB Hex format required in the docu. This could rather make sense as decimal in RSB as 00000100 = 4.

Any comments?

Regards,

Marc

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24 Apr 2021 15:35 #206954 by PCW
Masks are binary so 4 = 0100b -= joint 2

That is, the binary bit number is the joint
0x20 would be 0010000b = joint 5

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25 Apr 2021 21:36 #207044 by mwinterm
Thanks, was my mistake....

I interpreted LSB = Left Side Bit instead of Least Significant Bit.

Regards,

Marc

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29 Apr 2021 11:17 #207359 by andypugh
Does it actually work for you? I think that locking joints are currently limited to G0 moves only.

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29 Apr 2021 15:11 #207381 by mwinterm
Yes, that might be. Did not test it yet on the machine....

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03 Dec 2021 07:02 #228260 by HalaszAttila
I tested it with 2.8.2 version, the joint.N.unlock -> joint.N.is-unlocked pins are works just during homing. After the axis homed the brake locks (unlock pins goes to 0).

But neither G0 and G1 move does`t set the unlock pin to 1 before moving (is-unlocked pin = 0). The axis starts moving with locked brakes.

The axis jogging and MPG jogging is inhibited, like in preveous version (get alarm message).

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10 Jan 2022 00:03 #231270 by andypugh
I have just tested and I think that I am seeing the expected behaviour.
Though quite possibly the behaviour is not what is expected.

locking joints only works for rotary joints and joints associated with the axes A, B and C.

And even then, only with G0.

Which joints are and axes are you trying to use locking_indexer with?

I do think that the restrictions on locking_indexer are a bit arbitrary, I can see that the function would be useful for some other (rare) cases.

One case would be for running the machines that have one motor and a system of clutches. Though for thode to work it would need to be extended to G1. I am not sure that it would ever make sense to allow it with G2 or G3.

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