Adtech ADTECH9 Series Programming Manual page 27

Arc Interpolation Plane Definition Diagram
The end point of the arc is determined by address X, Y and Z. In G90 mode, i.e. absolute value mode, address
X, Y and Z specify the coordinate value of arc end in current coordinate system; in G91 mode, i.e. increment
value mode, address X, Y and Z specify the distance from the point of current tool to the end point in the
direction of every axis.
In X, Y and Z direction, the distance from the point of current point to the circle center is specified by address I,
J and K respectively, the symbols of which are determined by their motion directions.
The coordinate value of arc end can be either in absolute value or increment value, while the coordinate value
of arc center must be increment instruction from the start point.
When X, Y and Z are ignored (the start point coincides with the end point), I, J and K define the circle center,
and the track will be a full circle.
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Example:
G02 J50 F500;
G91 G02 X50 Y50 J50 F500;
The processing tracks are shown in the figures below (full circle and 3/4 arc)
ADTECH9 Series CNC Programming Manual
Instruction Diagram of Processing Full Circle