Siemens alarm 61931: Contour not closed

What it means

The contour interpreter reached the end of the contour description without returning to the starting point, i.e. the outline is open. Closed contours are mandatory for pockets/residual-material computation. Extend or correct the contour so it closes.

Likely causes

• Missing closing line/arc element in the contour subroutine
• Premature end of contour due to a jump or conditional block
• Coordinates mistyped so the last element misses the start point