Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 493)

Tool Control Functions
Chapter 20
20-9
Important: Any block that activates or deactivates a tool length offset
must be programmed in linear mode (G00 or G01) when executed. If a
tool change is made in the circular mode, no axis motion may take place in
the block changing the tool offset. The offset must be activated in a block
with no axis words.
When you program one of these TLO axis-select G-codes, the axis
programmed in the block becomes the axis to which the tool length offset
is applied; the forced axis name replaces the AMP-defined TLO axis.
Otherwise, these G-codes have the same effect as the G43/G44 codes.
Important: The G43.1 and G44.1 blocks are motion blocks; therefore, the
axis will move to the position (and offset) commanded in the block.
You must program a G49 before you can switch to a new TLO axis with
G43.1 or G44.1. You must also remove the offset from any previously
active TLO axis.
The axis that the control is currently using for tool length offset
calculations is shown in reverse video on the tool offset screen. An axis
shown in reverse video does not mean the offset is active, only that the axis
is the current tool length axis. An asterisk indicates the currently active
offset value.
The G10L10 and G10L11 offset table-modifier blocks now recognize axis
names to let you modify TLO data for axes other than the currently active
offset axis.
These conditions cause the AMP-defined TLO axis to become the active
axis, replacing the axis that was selected with a G43.1 or G44.1:
you perform a control reset
the AMP parameter Cancel Tool Offsets on M02/M30 has been set to yes
by the system installer, and an M02 or M30 block is executed
Switching planes with a G17/G18/G19 does not change the active TLO
axis; the active TLO axis can be switched only by programming a
G43.1/G44.1 with an axis name.
Copying Tool Length Offset Tables
Each selectable tool length axis has its own tool offset table and its own set
of offset values. For example, if you select the X-axis as the tool length
offset axis, you must enter an offset value for the X-axis for those tool
offsets to be used on X.
20.2.2
Tool Length Offset (TLO)
Axis Selection
(G43.1, G44.1)