28
+Z
+Y
+X
Y-Z plane
X-Y plane
Z-X plane
Plane
G17, G18 and G19
Setting the Measurement Unit
G20 and G21
Format
G17
G18
G19
Description
This specifies a two-dimensional plane for circular interpolation (G02 or G03).
G17 specifies the X-Y plane, G18 specifies the Z-X plane, and G19 specifies the Y-Z plane. Each of these is normally used in combina-
tion with G02 or G03 in the same block. (Refer to "Circular Interpolation G02 and G03").
Changing the measurement unit results in interpretation as shown below.
Format
G20
G21
Description
This sets the measurement unit used for movement, feed rate, and offset amounts. G20 sets inch input, and G21 sets millimeter input.
Either G20 or G21 is set at the start of the program, before setting the coordinate system. G20 and G21 should not be changed during
the course of a program.
The minimum units differ for inch input and millimeter input.
Command
G20
G21
G00X1.0
1 in.
1 mm
G00X1000
0.1 in.
1 mm
F60.0
60 inch/min.
60 mm/min.
F45000
4.5 inch/min.
45 mm/min.
G10P01R10.0
10 in.
10 mm
G10P01R10000
1 in.
10 mm
Movement
Feed rate
Offset amounts
Minimum units
0.0001 in.
0.001 mm
Inch input
Millimeter input