7. COORDINATE SYSTEM
Select the planes for circular interpolation, cutter compensation, and
coordinate rotation by G–code.
The following table lists G–codes and the planes selected by them.
Table 7.4 Plane selected by G code
Xp Yp Zp
G17 Xp Yp plane
G18 Zp Xp plane
X–axis or an
Y–axis or an
Z–axis or an
G19 Yp Zp plane
to it to it to it
Xp, Yp, Zp are determined by the axis address appeared in the block in
which G17, G18 or G19 is commanded.
When an axis address is omitted in G17, G18 or G19 block, it is assumed
that the addresses of basic three axes are omitted.
Parameter No. 1022 is used to specify that an optional axis be parallel to
the each axis of the X, Y–, and Z–axes as the basic three axes.
The plane is unchanged in the block in which G17, G18 or G19 is not
When the power is turned on or the CNC is reset, G17 (XY plane), G18
(ZX plane), or G19 (YZ plane) is selected by bits 1 (G18) and 2 (G19) of
The movement instruction is irrelevant to the plane selection.
Plane selection when the X–axis is parallel with the U–axis.
G17X_Y_ XY plane,
G17U_Y_ UY plane
G18X_Z_ ZX plane
X_Y_ Plane is unchanged (ZX plane)
G17 XY plane
G18 ZX plane
G17 U_ UY plane
G18Y_ ; ZX plane, Y axis moves regardless without any
relation to the plane.