no option to home just Y axis on gantry with 2 Y motors

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09 Feb 2022 14:43 #234394 by dbotos
My table has no home or limit switches - I just zero G53 coordinates using homing and run programs from there.

The homing menu entry in the Axis GUI under 2.8.2 is only showing me options to home all, home X, or home Z.  No option to home Y.  See attached pic.

Is this something I can force-enable in the config files (latest rendition attached for my laser setup)?

Thanks,
David
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09 Feb 2022 15:37 #234397 by tommylight
You have home_sequence set to -2 for Y axis, hence it will only home if there are switches on both sides.
Most probably setting that to a positive value will work as you have it set for immediate homing.

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09 Feb 2022 18:46 #234404 by dbotos
I'll try changing those Y1 and Y2 HOME_SEQUENCE values this evening and report back.

Couple other questions:

1. What keeps the machine from trying to move and find home via switches?  The fact that my HOME_SEARCH_VEL for all joints is zero?  I don't have it explicitly defined for any joint, but zero is what it defaults to (per section 8.3.6.13 of the 2.8.2 documentation).

2. When LinuxCNC first opens up, is it in joint mode or axes mode?  I saw several references to joint mode in the 2.8.2 documentation, but they didn't explicitly answer this question.

 

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09 Feb 2022 20:45 #234424 by tommylight
linuxcnc.org/docs/html/config/ini-homing.html#_immediate_homing
linuxcnc.org/docs/html/motion/kinematics.html#_joints_vs_axes
If you are using Axis GUI, on the bottom there is always written what is active, axis mode or joint mode and that can be changed at any time using Shift+3 or Shift +4 <<not sure.

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10 Feb 2022 03:07 #234456 by dbotos
No luck.  Tried them as both 0, both 1, both 2, and then one 2 and the other 3.

I also tried getting rid of the HOME_SEQUENCE lines, which changes the the Home All button to Home Axis (see attached screenshots and excerpt from documentation below), but when the Y axis radio button is selected, the Home Axis button does nothing.

(from 4.1.3.5 in the 2.8.2 documentation:

If not all axes have valid home sequences, the homing button will show Home Axis and will home the joint for the currently selected axis only. Each axis must be selected and homed separately.)

I don't see anything at the bottom of Axis for the joint/axes mode - it just has machine state (ESTOP, OFF, ON), tool, and position offset and feedback types.
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10 Feb 2022 14:57 #234486 by tommylight
I thought so, but it was worth a try.
Tandem axis will most probably not home without switches as that is the main purpose of having tandem axis.
Seems you will have to do a normal XYZ config and wire both drives to the same output either in hal or physical wiring.

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10 Feb 2022 23:58 - 10 Feb 2022 23:59 #234540 by dbotos
That sounds like a PITA.  Could a "Home Y" button be added with GladeVCP?  It would need to (1) zero the G53 Y position and (2) mark that axis as homed.  Which doesn't seem impossible since Axis does that to the Y axis (along with the X and Z axes) when you press Home All.
Last edit: 10 Feb 2022 23:59 by dbotos.

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11 Feb 2022 13:54 - 11 Feb 2022 15:09 #234572 by Todd Zuercher
Yes, to home a gantry axis by itself you can use the Halui pins "halui.joint.N.home" for all of the joints involved in the gantry axis. Simply net those together with the hal output pin from a VCP button or a real button. For example:
net HOME-Y <= gladevcp.button1 => halui.joint.1.home => halui.joint.3.home

 
Last edit: 11 Feb 2022 15:09 by Todd Zuercher.

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11 Feb 2022 17:59 #234596 by dbotos
Cool - I will give that a try.

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13 Feb 2022 20:23 - 13 Feb 2022 20:24 #234739 by dbotos
I created a UI in Glade 3.8.6-1 and saved it as "dbotos_laser_2_8_vcp.ui".  It has a button is there for homing Y and I also threw in a meter for percent full power of the laser.

I created an associated HAL file named "dbotos_laser_2_8_vcp.hal" and put the line in there suggested by Todd (with a modification for the button id).  I didn't put anything in there for the meter yet.

And, I modified my INI file as follows:

In the [DISPLAY] section, added:
GLADEVCP = -u ./dbotos_laser_2_8_vcp.ui

In the [HAL] section, added:
POSTGUI_HALFILE = ./dbotos_laser_2_8_vcp.hal

When I tried to run LinuxCNC with my dbotos_laser_2_8 config, it gave the following error:
Warning: Forward kinematics must handle duplicate coordinate letters:yy Note: Individual axis homing is not currently supported for KINEMATICS_IDENTITY with duplicate axis letter Embeded tab command "halcmd loadusr -Wn gladevcp gladevcp -c gladevcp -x 44040335 -u ./dbotos_laser_2_8_vcp.ui" exited with error: 1
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Last edit: 13 Feb 2022 20:24 by dbotos.

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