Revise Misleading IDEX Comment

[InsanityAutomation]

As discussed in #22998 the comment here is incorrect and has led to many configuration issues. The X2 Max Position is the softendstop position, and defaults to also be used as the home position for the axis. Therefore it should be referencing the limit from X0 not from the other toolhead, which is typically homed to a negative X value.

[thinkyhead]

• Is there any scenario where X_MAX_POS is farther than the X2_HOME_POS ?
• Could it be that some code is using X_MAX_POS where it should be using X2_HOME_POS ?

With Dual X Carriage the X2_MAX_POS is used in the following contexts in motion.cpp…

hotend_offset[1].x = _MAX(X2_HOME_POS, X2_MAX_POS)
const float dual_max_x = _MAX(hotend_offset[1].x, X2_MAX_POS);

If the X2_MAX_POS is no different from the X2_HOME_POS then you might try to combine them and reduce the number of configuration options by one.

[InsanityAutomation]

X max should be X2 max - head width to prevent crashes when x2 is parked.

[InsanityAutomation]

Also, X Max can never be greater than X2 Max or home position because it would have to move through the other head to do so.

On mobile, so been responding bit by bit... The only reason that you might have a difference between the X2 maximum and home is to allow clearance off of the switch and not allow the tool to sit there compressing it constantly depending on the type of end stop. It could also be in the case of a rear mounted home switch with a purge block further to the right.