How to. 2 or more motors on one axis. Gantry

On your Y axis joints (joints 1 &2), change the home sequence on both to equal -1

[JOINT_1]
TYPE = LINEAR
HOME = 0.0 This is the final home position
MIN_LIMIT = -0.001
MAX_LIMIT = 1220.0
MAX_VELOCITY = 200.0
MAX_ACCELERATION = 500.0
STEPGEN_MAXACCEL = 625.0
SCALE = 106.666666667
FERROR = 1
MIN_FERROR = .25
HOME_OFFSET = 0.0 This is used to square the gantry (a small number) ie 0.25
HOME_SEARCH_VEL = 0 use this to search for the home switch ( if you change the sign it will reverse the direction) if it is zero it probably won't move
HOME_LATCH_VEL = 0 This number is set to the speed of the search to the switch ( if you change the sign it will reverse the direction)
HOME_USE_INDEX = NO
HOME_SEQUENCE = 0 It is usual to have 0 for the Z axis (so that the Z will lift out of the way first) but for dual homing both axis have to have the same -ve number ie -1

Thanks for the help, the -1 did it. now, after homing, which at the moment does nothing, everything moves correctly.

I don't quite understand now, how I need to setup the homing. I don't want you use two endstops on Y, the system is rigid enough for me that homing on one side schould be enough for my needs.
Is there a good explanation on how to setup the hal/ini file for homing switch inputs? I think I can't use stepconf anymore, because that would override my previous changes, correct?
Clives explanations were very helpful, but I don't understand the difference between HOME_LATCH_VEL and HOME_SEARCH_VEL yet.

Yes, now you have a working config. forget pncconf and edit by hand

Homing is describered here. Read it all but check out section 5 for all the velocities.
linuxcnc.org/docs/2.8/html/config/ini-homing.html

The whole thing about gantry machines is the use of two home switches allows the gantry to be squared when it homes.

Clives explanations were very helpful, but I don't understand the difference between HOME_LATCH_VEL and HOME_SEARCH_VEL yet.

HOME_SEARCH_VEL is the speed at which you want to run to the home switch (which is generally slower than a G0 move) The search for home is at a reasonable speed and might overshoot slightly.

HOME_LATCH_VEL Is the speed Usually very slow to back off the home switch (this is the final trigger and accurate move) when this is done you use the HOME to move away from the latch so that it will not get false triggers (this can be 1mm to the other end of the table if you want.

Once this is all done and homed the soft-limits will work correctly.

As Rod has said you need a switch (sensor) at either side of the gantry to be able to square it with the HOME_OFFSET.

I updated the github 2.8 configs/by_interface/parport/gantry configs.

I also attached a zip to the following thread.
forum.linuxcnc.org/49-basic-configuratio...tors?start=20#236206

My intent is to have a good gantry example included in the released configs. I think this example includes most the great information found in this thread. My update uses XYZY, instead of XYYZ favored in this thread because it matched the initial stepconf XYZA config better.

I think it's significant to include gantry_joints.ini to use the same .hal and minimal changes to allow joint mode jogging (while debugging the machine). But once the machine is wired correctly there is no reason to deal with joint mode.