Every CNC control has a mode selector, and the mode decides which buttons do what. Names and switch positions vary between control makers, but the same handful of modes appear on almost every machine.
The common modes
Auto (memory)
- What it does
- Runs a stored part program from start to end
- Used for
- Production
MDI (Manual Data Input)
- What it does
- Runs lines typed in at the control
- Used for
- Tool changes, spindle start, quick moves
Jog
- What it does
- Moves an axis while a direction key is held
- Used for
- Positioning during setup
Handwheel
- What it does
- Moves an axis with the hand pulse generator
- Used for
- Fine positioning, touching off
Edit
- What it does
- Creates or changes programs in memory
- Used for
- Program corrections at the machine
Reference / home
- What it does
- Sends axes to their reference position
- Used for
- After power-on, to restore position
| Mode | What it does | Used for |
|---|---|---|
| Auto (memory) | Runs a stored part program from start to end | Production |
| MDI (Manual Data Input) | Runs lines typed in at the control | Tool changes, spindle start, quick moves |
| Jog | Moves an axis while a direction key is held | Positioning during setup |
| Handwheel | Moves an axis with the hand pulse generator | Fine positioning, touching off |
| Edit | Creates or changes programs in memory | Program corrections at the machine |
| Reference / home | Sends axes to their reference position | After power-on, to restore position |
Two options often sit beside the mode selector: single block, which pauses after every line of a program, and dry run, which runs it without cutting to check the path.
Auto vs MDI
Auto is how parts get made: the control works through a saved, proven G-code program. MDI is a shortcut — handy for a tool change or a warm-up command, but what is typed isn’t saved or proven the way a program is, so a typing mistake runs immediately. Most shops keep MDI for setup and keep production in Auto.
What the mode tells you
The mode, read alongside whether a program is running, explains a stop. A machine sitting in Jog or MDI with no program running is usually being set up or adjusted; a machine in Auto with the program on hold has been paused mid-cycle. Both look “stopped” from across the floor.
On controls that report it, ThingConnect reads the mode and the execution state from the controller and shows them in plain words on the machine’s live screen — for example “Auto (memory)” and “Hold” — so a supervisor can tell a setup from a stalled cycle without walking over.