Which command is used to activate cutter compensation for height offset 4?

The command that activates cutter compensation for height offset 4 is G43. This command is used in CNC programming to enable tool height offsets, which help to ensure that the cutting tool is positioned at the correct height relative to the workpiece.

When G43 is invoked, it typically requires the tool height offset number to be specified, which in this case would be offset 4. By using G43 with the appropriate offset, the CNC machine knows to adjust the Z-axis position according to the predefined height for that specific tool, ensuring accurate machining without errors due to differences in tool lengths.

The other commands listed have specific functions but do not relate to height offsets. For example, G20 is used for setting the unit of measurement to inches, G40 cancels cutter radius compensation, and G17 selects the XY plane for circular interpolation. Each of these has its unique purpose, distinct from managing tool height offsets.