Syntax & Parameters

G81 followed by axis, R & F value.
X, Y, Z, A, B Value - specifies the axis you wish to move following the distance to move. The distance value will be the current machine units in use.
R Value - This is the retract position in the Z axis. This value must be specified.
K Value - This is number of time the cycle needs to be repeated. (Optional)
F Value - The F value defines the feed rate at which the axis will move at.

Example program

N10 G99 G81 X10 Y10 Z-8 R2 K2 F100
N20 X20
N30 X30
N40 G80

The first line moves the X & Y axis to 10mm position with retract plane set to 2mm, drilling to Z -8mm at 100 mm/minute feed rate and starts drilling.
The K value of 2 will cause the drill cycle to repeat a 2nd time drilling the hole again before moving on to the next line of Gcode.
The second line moves X axis to 20mm position and drill a hole as per the same values.
The third line moves X axis to 30mm position and drill a hole as per the same values.
G80 cancels the canned cycle.

INFORMATION: Units are defined as either inches or mm depending on your machines setup or if G20 or G21 command in use.

WARNING: Before a new canned cycle can be used the previous one must be cancelled with a G80