Program with tool change results in "Exceeds Z-axis" warning

I've got a tool rack on my gantry CNC router. Generally, tool changes work very well, invoking a couple different g-code programs to carry it out. Manually-invoked automatic tool changes work well.

But if I load a program that calls for a tool change to a different tool than what's currently in the spindle, Axis throws up an error that the program exceeds the z-axis limits. Any idea why that might be, or how I might debug this? I've attached the relevant code.

are you setting your tool change location with g28.1 ? and calling g28 on a tool change ?

also g53 calls machine co-ordinates, and g59.3 calls relative co-cordinates. 

you need to use machine absolute postion.



couple of thoughts after browsing the gcode involved here. 

1. write a seperate macro to call the Z axis position. Using MACHINE co-ordinates, call that macro when moving the spindle. 
2. write this as a hal component. 
3. use carousel " if you can and are" to position the turret. 
4. use pocket numbers " as long as it is a umbrella type changer and not set into random toolchanger mode " 
5. keep your tool number and pocket numbers aligned.
6. write a homing routine to HOME the tool turret or belt or whatever prior to running the machine.