M Code

Definition

Instruction set used for auxiliary function control. Treat it as a machine-side action set that must match the builder and controller conventions.

Formula / Rule

• M-codes control spindle, coolant, stops, clamps, tool change, and other auxiliary actions.
• Execution timing can vary by controller, so read the machine manual together with the NC block.

Typical Range

• Use it at tool changes, cycle boundaries, safe stops, and machine-specific actions.

Shop-floor Scenarios

• Confirm spindle and coolant commands before the first cut after a restart.
• Verify optional stop and end-of-program behavior during prove-out.

Common Errors / Troubleshooting

• If a machine response is missing, check whether that controller remaps or disables the M-code.
• If sequencing feels wrong, inspect block order, dwell, and machine builder options.

Related Tools

• G/M Code Reference
• G-code Viewer