Gantry with 2 Synced Y Axis motors, X axis jogging not possible when not homed

Hi, I have a Gantry CNC with 4 Motors on X Y Y and Z. Everything works but, I have a question regarding the jog of the Y Axis when not homed. 

The joints are 
Joint 0 Z 
Homing Sequence 0
Joint 1 Y
Homing Sequence -1
Joint 2 Y
Homing Sequence -1
Joint 3 X 
Homing Sequence 1

If I home the machine, first Z then X and Y home together. If the machine is not homed, I can not jog with the X axis. LinuxCNC says an error because of the Y is synced and in the same sequence.

As a workaround I have increased the Y sequence to -2 on both joints. Now, I can jog X when not homed. Down side homing goes Z then X then Y. 

Is there a way that Y gets locked from jogging when not homed and in the home cycle X and Y work together?

Mike

You need to home a joint axis before it can be jogged. Correct workflow is power up, home all, then jog.
I have never tried to home a joint axis with another axis. MAybe it will lif you make X = +2

A bit of HAL work can allow jogging before homing on synchronised joints. 
linuxcnc.org/docs/2.9/html/config/ini-ho...l#_inhibiting_homing
 

@phillc54 Awesome, that was what I was looking for. Will try that, thank you.

@rodw You are right, but there are reasons when I just want to move the machine from the park position a little bit, without homing,...

@phillc54: That worked partly. I am followed the link and implemented that in the machine. I am now able to jog trigger the signal on the GUI and jog the x and y axis. I will update the manual, since there are a few informations missing, but I figured it out.

My problem now is: When I jog the Y axis with the 2 synced motors when they are NOT homed, only one motor moves when I click on the Y + or - button in the GUI. I believe I have to implement another button to move both motors at the same time, but not sure.

You would need to connect both the joints for Y to the Y jog button because you would normally want them both to jog together.

 

Just checked the hal file and the machine hal configuration, I can not find where the Buttons are connected to anything. Do you know where to find them?

You won't be able to use the existing GUI buttons for synchronous unhomed jogging unless you rewrite/hijack some of the GUI code.
It is best done with an MPG, as all jogging really is.
You could probably add a button in a panel to jog the two joints, the simulation axis/gantry/gantry_jjog would be a good starting point.


Edit: What GUI are you using?

I am using the AXIS gui. I looked at this gantry_jjog. I only found that in the documentation of LinuxCNC 2.5. I am using the trivkins. I looked in the manpage and found that I had to add kinstype=b to the Ini file. Now I can switch with the $ shortcut between XYZ axis jogging and joggining for the individual joints. A step ahead!

This is a step in the right direction. I tried to find the signals which I need to connect now in joint mode to move joint 1 and 2 at the same time. I guess it must be something with Joing count and joint scale. I searched for all, but can not find anything which changes when I use the regular axis +/- buttons.

Note Homing changed significantly with 2.8 so stuff on 2.5 is likely not relevant.
I think G10 works on the current G5X space. You may have G54 set in your preamble