# Reaction on contour change

A direct contour change, e.g. from G41 to G42, is permitted without any explicit deselection (G40) of TRC. The contour change corresponds to a TRC deselection and selection. Contour change should only be carried out for linear NC blocks for exit and approach blocks. Circular blocks are also permitted directly before and after a contour change.

## Notice

If a circular block is programmed during a contour change, an error message is output.

## Programing Example

Reaction on contour change

N05 G01 Y10 F100 G41 V.G.WZR=2 | (Linear block with select. of TRC left) (of the contour )
N10 X20 Y25 |
N20 X40 G42 | (Linear block with select. of TRC right) (of the contour)
N30 X60 Y10 |
N40 X0 Y0 G40 | (Deselect TRC)
N50 M30 |

Example of a selection change without deselection