G38.2 – Straight Probe Cycle - MASSO Documentation

The G38.2 command is used for probing parts or fixtures.

When a G38.2 command is executed, the specified axis will move towards the defined position until the probe input is triggered. If the probe does not trigger before the axis reaches the specified position, the program will stop and an alarm will be displayed on the screen.

To use the G38.2 command, a probe input must be assigned. The probe input must change state from Low to High when the probe is triggered.

Syntax & Parameters

The X, Y, Z, A, or B value specifies the axis to be used for probing and the maximum machine coordinate that the axis is allowed to move towards. The distance value uses the current machine units.

The F value defines the feed rate at which the probing move will occur.

Example ProgramN10 G38.2 Z-10 F100

In the above example, the Z axis moves towards the machine coordinate Z-10 while monitoring the probe input. When the probe touches, the Z axis stops immediately and the program continues to the next G-code line. If the probe does not trigger before reaching Z-10, the program stops and an alarm is displayed on the screen.

The coordinate value specified in the G38.2 command is always interpreted as a machine coordinate.

Example Program – Plasma Torch Height Setup

A common use of the G38.2 command is in conjunction with G92 to set the initial torch height on plasma machines.

N10 G38.2 Z-50 N20 G92 Z0 N30 G0 Z1

In this example, the G38.2 command probes the Z axis towards the material surface. When the probe input is triggered, the Z axis stops.

The G92 Z0 command then applies a temporary work offset to set the current Z position as Z0.

Finally, G0 Z1 moves the Z axis one unit above the material surface, setting the correct cutting height.

INFORMATION: Units are defined as either inches or millimetres, depending on the machine setup or whether G20 or G21 is active.