CAM offset number to G-code
| CAM work offset | FANUC output | Haas output |
|---|---|---|
| 1–6 | G54–G59 | G54–G59 |
| 7+ | G54.1 P1, P2, ... | G154 P1, P2, ... |
Some CAM systems start at 0 (meaning G54), others at 1. The post must know the convention, or every offset is shifted by one.
Extended offsets
With the additional work coordinate option, FANUC provides 48 extended offsets (G54.1 P1–P48), and up to 300 on some controls. These are essential for tombstones and multi-part fixtures with many parts.
Programmable offsets with G10
(Set G55 from the program - FANUC)
G10 L2 P2 X-250.000 Y-120.000 Z-310.500
(Set extended offset P5)
G10 L20 P5 X-400. Y-120. Z-310.5Posts can write offsets from CAM fixture data or probing results, useful for fixed fixtures with known positions.
Multi-part fixtures
(Same operation repeated for 4 parts)
G54 (... op ...)
G55 (... op ...)
G56 (... op ...)
G57 (... op ...)The post can repeat each operation per offset, or use subprograms called at each offset to keep the program short.
Common offset mistakes
- Off-by-one numbering between CAM and post.
- Extended offsets output in the wrong format for the controller.
- Offset change without a safe retract between fixtures.
- Setup sheet showing a different offset than the program.
A work offset is a promise between programmer and operator. The post should keep it.
Work offset handling in posts
See our CNC post processor development service and work coordinate systems.