
8.
COORDINATE VALUE AND DIMENSION
8.2 Inch/Metric Conversion (020, G21)
8.2 Inch/Metric Conversion (G20, G21)
Either inch or metric input can be selected by G code.
Unit systems
G code
Least setting
increment
Inch
G20
. 0.0001 inch
Millimeter
I
G21
I
0.001 mm
This G code must be specified in an independent block before setting the coordi-nate
system at the beginning of the program. The unit systems of the following items can
be changed with G codes:
(1)
Positional command
(2)
Feedrate by F command
(3)
Offset values
(4
Unit of scale for manual pulse generator
0
Movement distance in step feed
(6)
Some parameters
(Note 1) When the power is turned on, the NC status is the same as mat held before the power was turned
off.
(Note 2) G20 and G21 must not be switched during a program.
(Note 3) When the machine unit ahd the input unit systems are different, the maximum error is half of the least
command increment. This error is not accumulated.
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