Conversion of NC Program Code to G91

Converting NC Program Code: G90 → G91

NCPlayer provides an automatic conversion feature for transforming an NC program (part program) from the absolute coordinate system (G90) to the incremental coordinate system (G91). This makes it easier to edit and adapt programs for machines that require incremental moves for each command.

How it works

• If the program does not explicitly specify G90/G91 mode, G91 is inserted at the beginning.
• All coordinates in motion commands (G0, G1, G2, G3, etc.) are recalculated relative to the previous position.
• At the end of the program or the selected block, G90 is automatically added to return to absolute mode.
• Comments and code structure are preserved.
• If before inserting G91 there was a G0 move along the Z-axis, it remains unchanged to prevent positioning errors.

Example conversion

Before:
G90 G0 X0 Y0
G1 X50 Y50
G1 X100 Y100

After:
G91
G0 X0 Y0
G1 X50 Y50
G1 X50 Y50
G90

When to use

Converting G90 → G91 is useful for:

• Writing repetitive movement cycles.
• Optimizing programs for CNC machines with simplified controllers.
• Minimizing the effect of accumulated positioning errors during long movements.