Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 491)

Tool Control Functions
Chapter 20
20-7
Figure 20.4
Results of Example 20.1
Z-100
Gauge
Line
Case 1
G49
No offset active
Case 2
G43
Positive geometry
offset in table Case 3
G44
Negative geometry
offset in table
Offset “H00” in the offset table is always equal to a value of zero, but does
not cancel the tool offset mode like G49. HOO cancels H--words.
Programming a G49 will not change the current H--word to H00.
Example 20.2 illustrates this.
Example 20.2
Modal G43, G44 and Modal H- words
Program Block Comment
N1G00G90;
N2G43 H01; G43 mode, H01 offset
N3 ; G43 mode, H01 offset
N4H02; G43 mode, H02 offset
N5; G43 mode, H02 offset
N6G44 G44 mode, H02 offset
N7; G44 mode, H02 offset
N8G49; Offset mode cancelled, H02 offset
N9G43; G43 mode, H02 offset
N10H0; G43 mode, No offset value
N11G44; G44 mode, No offset value
Important: Whenever a new tool length offset is initiated or cancelled, the
block that changes the offset must be a linear block (G00 or G01). In the
above example, blocks N2, N4, N6, and N8 must be linear blocks.