@gloomyandy Hello ,
Sorry for the late reply. Was on vacation for few days. I have continued the "experiment". Ignore the number of extruder drivers i had above. I rewired and reconfigured everything to the very simple set up. I have a Duet 3 mini 5+ board with CAN expansion motor board and a tool board. I have X;Y;Z set up via the motor board and the tool axes from the tool board. I have a stepper motor connected to the mini board and i configured it as U axis. It is just for the experimental set up. (My intended use is to load filament in the other tool while the machine is printing). So the U axis is my fake tool for example. I am just experimenting before i want to really implement it.
My findings so far.:

• With the firmware version 3.5.3 , it is working.
• With the firmware version 3.6.0.beta1 i am getting the error that i reported before.
  The video with the version 3.6 is
  20241113_171849.mp4
  daemon(1).g config(3).g .
  Thank you .

@Alva I tried another test, while the machine was printing i trigerred daemon with a flag global.called and created the condition when global.called= true to select the second motion system and move the W axis. then the axes moved to the Y max and crashed and machine still remains in the printing state doing nothing.

@gloomyandy i am just setting the led strip colors of the corresponding active tool and moving the u or w axes based on which tool is activated to its minimum position

the same ocurred to me but it happened when i was experimenting with the second motion system. While the machine was printing , i wanted to move the unused axes. i have trigerred a flag in daemon.g to select the next motion system and move W axes and machine started moving to a different place and stopped. and the machine is still in printing state

@droftarts Is there any way to print back the axes used by the motion systems? I have tried the sample code that you have sent me above and it resulted in the error as shown in the figure below.
. I tested the above piece of code as a macro. In my system i have X, Y, Z, U , W axes and tool 0 is moved by u and tool 1 by w axes.

echo "start testing 2nd motion system"
T0
G1 X100 Y100 Z25 E0.1 F1000
G1 X110 Y100 E0.1 F1000
M596 P1 ; selects the second motion system
T1      ; select tool (set temperature changes from standby to active temperature)
M568 P1 S200 R200 ; wait for temperature to be reached
G1 E5 F1000 ; prime extruder
M596 P0 ; change back to first motion system, while the above happens
G1 X120 Y100 E0.1 F1000
M400 ; wait until motion stops, release owned axes and extruders from motion systems
T1 ; first motion system takes over T1, parking T0.
echo "done testing 2nd motion system"

Line number 6 is selection of the tool and is clearly not X axis.

Hello,
I am trying to experiment with the second motion system. I was reading the whole documentation about the second motion system and couldn't really understand how to assign the unused axes to the second motion system. Can someone please help me understanding the concept? How do i map the unused axes to the second motion system? Thank you

M596 P1 ; selects the second motion system.

I want to somehow maps the unused tool to the second motion system