G-Code

Definition

The most widely used programming language for CNC machines. G-code commands control machine movements, spindle operations, coolant, and other functions through standardized alphanumeric codes. Read it together with modal state, active plane, offsets, and controller dialect.

Formula / Rule

• G-codes set motion, modal behavior, planes, compensation, and datum logic.
• The same block can contain coordinates, feed, spindle, and auxiliary commands that must be read as one state.

Typical Range

• Use it in every toolpath block, but judge meaning by the active modal context instead of the letter alone.

Shop-floor Scenarios

• Check startup blocks first when restarting a part or loading a transferred program.
• Compare posted code with the controller manual before dry run on a new machine.

Common Errors / Troubleshooting

• If motion is unexpected, confirm the active plane, positioning mode, and compensation state before editing geometry.
• If output differs between machines, verify controller dialect and post-processor settings.

Related Tools

• G-code Viewer
• G-code Reference