G20 Inch programming check / Select inches

Haas NGC G-code · Mill, Lathe

On mills: Inch programming check

Tells the control the program is in inches. On Haas the units are set by Setting 9, and G20 checks that the setting matches.

Format

G20

How it works

Modal, units group 06.

Example program

O01000 (INCH PROGRAM)
G20 (CONFIRM INCH MODE)
G17 G40 G80 G90 (SAFE START)

Example is in inch. Check offsets and clearances first.

Watch out for

If Setting 9 is set to metric, a G20 line stops the program with an alarm instead of switching units.
Change Setting 9 before loading offsets, since offsets are stored in the current units.

On lathes: Select inches

Confirms the program is in inch. Use Setting 9 to choose inch or metric. G20 alarms if Setting 9 is not set to inch.

Format

G20

How it works

Modal, group 06.

Example program

G00 G18 G20 G40 G80 G99 (SAFE STARTUP, INCH)
T0101 (OD TOOL)
G00 G54 X2.1 Z.1 (APPROACH, VALUES IN INCHES)

Example is in inch. Check offsets and clearances first.

Watch out for

G20 does not switch the units on a Haas. It checks them. Set Setting 9 first.

Related codes

G21

G20 on other controls

The same number can mean something different on another control.

Control	Meaning
Fanuc	Inch input
Mazak (EIA)	Inch input
Okuma OSP	Inch input confirmation
Mitsubishi M70 M80	Inch input
Brother Speedio	Inch input
Fagor 8055 8065	Lower work zone limits (8055)
LinuxCNC Tormach	Inch units
Mach3 Mach4	Inch units
Centroid CNC12 Acorn	Inch units
Hurco WinMax (NC)	Inch input (ISNC)
Fadal	Check for inch setting
Swiss (Citizen Star)	Inch input

Every G-code for Haas NGC in your pocket. The app has the full example programs, search by number or shop word, a line decoder and calculators for tapping, threading and drilling.

Open G20 in the app All Haas NGC G-codes

App Store Google Play