AC Absolute or incremental value for one axis

Siemens 840D 828D G-code · Mill and lathe

AC() makes one coordinate absolute while G91 stays active. IC() makes one coordinate incremental while G90 stays active. Both also work for arc center values.

Format

X=AC(value) or X=IC(value)

Addresses

Address	What it does
`X=AC()`	Absolute value for this axis, this block only
`X=IC()`	Incremental value for this axis, this block only
`I=AC()`	Absolute arc center

How it works

Non modal. Only the coordinate written with it is affected.

Example program

G90 G0 X0 Y0 ; ABSOLUTE
G1 X=IC(10) Y20 F300 ; X MOVES 10 MORE, Y GOES TO 20
G91 G1 X5 Z=AC(-2) ; X INCREMENTAL, Z ABSOLUTE
G90 ; BACK TO ABSOLUTE

Example is in inch. Check offsets and clearances first.

Watch out for

The equal sign is required: X=AC(20).
Rotary axes use DC, ACP and ACN for shortest way or forced direction instead of AC.

Related codes

G90 · G91 · G2

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