
B–63522EN/02
8. COORDINATE VALUE AND
DIMENSION
NC FUNCTION
109
There are two ways to command travels to the axes; the absolute
command, and the incremental command. In the absolute command,
coordinate value of the end point is programmed; in the incremental
command, move distance of the axis itself is programmed.
G90 and G91 are used to command absolute or incremental command.
G90 : Absolute command
G91 : Incremental command
100.040.0
30.0
70.0
Y
End point
Start point
For the above figure, incremental command programming results in:
G91 X60.0 Y40.0 ;
while absolute command programming results in:
G90 X40.0 Y70.0 ;
Absolute/incremental command, when G code system A at T series is
selected, is not distinguished by G90/G91 but is distinguished by the
address word.
For the A and B axes, no incremental commands are provided.
Absolute command Incremental command Notes
X U X axis move command
Z W Z axis move command
Y V Y axis move command
C H C axis move command
A None A axis move command
B None B axis move command
Example
X_ W_ ;
Incremental command (Z axis move command)
Absolute command (X axis move command)
8.1
ABSOLUTE AND
INCREMENTAL
PROGRAMMING
(G90, G91)