G Code

G-Code

This page tries to describe the flavour of G-codes that the machine firmware uses and how they work

Updated Feb 12, 2014 by mrmarios97

Field	Functionality
Gnnn	Standard G Code command
Mnnn	Miscellaneous commands' field
Tnnn	Define tool (in this case it is only one)
Xnnn	X coordinate field
Ynnn	Y coordinate field
Znnn	Z coordinate field
Fnnn	Feedrate (speed in deg/sec)
Pnnn	Time (in msec)
Rnnn	Radius (not used at the moment)
Nnnn	Command queue number

Command	Name	Description	Parameters	Used	Example
G0	Rapid Positioning	Move Rapidly to point M(x,y,z)	X,Y,Z,F	Yes	G0 X23 Y34 F200
G1	Linear Interpolation	Controlled move in a straight line to point M(x,y,z)	X,Y,Z,F	Yes	G1 X32 F50
G2	Circular Interpolation	Controlled circular move towards an arc CW	X,Y,Z,R,F	Yes	G2 X20 R2
G3	Same as above but CCW			Yes	G3 X20 R2
G4	Dwell	Do nothing for a defined time (in msec)	P	Yes	G4 P300
G17	XY Plane			No	G17
G18	XZ Plane			No	G18
G19	YZ Plane			No	G19
G20	Coordinates to in	All units are now in Inches (UK Metric System)		No	G20
G21	Coordinates to mm	All units are now in Millimeters `10^(-3) m` (S.I.)		No	G21
G28	Move to origin	Move to zero endstops You can define which axis would be zeroed	X,Y,Z	Yes	G28 X0 Z25.4
G90	Absolute Positioning System	Programming from now on will be employed in Absolute Positioning System (APS)		Yes	G90
G91	Relative Positioning System	Programming from now on will be employed in Relative Positioning System (RPS)		Yes	G91

Codes with command numbers less than 10 can be written by adding a 0 (zero) in front of them. e.g. G1 is the same as G01

In APS the set of all points is described relative to the starting point (a.k.a. the "home point" W). An example will be more comprehensive:

Point	X	Y	Z
W	0	0	0
A	24	10.5	30
B	30	15	32

In RPS all coordinates are relative to the last position.

You must define the Unit System you're working with (Inches or Millimeters)

The usage of Inches (in) as a unit for length is at the momment being used only in UK.

The usage of Millimeters (mm) as a unit for length is used worldwide as a submultiple of 1m (S.I.) and it is equal to 1/1000 m

Command	Name	Description	Used	Example
M0	Stop	Scheduled machine pause	Yes	M0
M1	Sleep	Optional machine sleep	Yes	M1
M2	Finish	End of program	Yes	M2
M6	Tool Change	Only one tool is available	No
M30	Loop Program	Ends the current program and returns to its beginning	Yes

Command	Name	Description	Parameters	Used	Example
T1	Tool #1	The only tool being used for the time being		No	T1

Point	X	Y	Z
W	0	0	0
1	10	-10	2
2	9	12	4

T1 
G0 X10 Y-10 Z2 F200
G1 X9 Y12 Z4 F150
M3