What are the differences between MDI Commands and G Commands?

MDI (Manual Data Input) commands and G (Geometry) commands are both types of commands used in CNC (Computer Numerical Control) machines to control the machining operations. However, there are some key differences between MDI commands and G commands:

1. Input Method: MDI commands are manually entered into the machine’s control system in real-time during manual operation, typically through the control panel or keyboard. On the other hand, G commands are typically pre-programmed in the CNC program and are executed automatically during the program execution.
2. Real-time Control: MDI commands allow operators to have real-time control over the machine’s movements and operations. Operators can input MDI commands on the fly and see immediate results, making it useful for manual machining or troubleshooting purposes. In contrast, G commands are pre-programmed in the CNC program and are executed sequentially during program execution, without real-time operator intervention.
3. Immediate Execution: MDI commands are immediately executed by the machine’s control system once entered, allowing for immediate control and feedback. G commands, on the other hand, are executed sequentially as part of the CNC program during program execution, following the programmed order of operations.
4. Flexibility: MDI commands offer more flexibility as they can be entered, modified, or canceled on the fly during machine operation, providing real-time adjustments to the machining process. G commands, on the other hand, are fixed in the CNC program and cannot be changed during program execution without modifying the program.
5. Syntax and Functionality: MDI commands and G commands have different syntax and functionality. MDI commands are typically simple one-line commands entered manually, while G commands are more complex and are used to specify various machining operations, such as rapid positioning, linear or circular interpolation, tool compensation, and more.
6. Programming Requirements: MDI commands do not require prior programming and can be entered directly by the operator during manual operation. G commands, on the other hand, require programming in the CNC program before they can be executed during program execution.
7. Error Checking: MDI commands are entered manually and may be more prone to human error, as they do not have the same level of error checking as G commands programmed in the CNC program. G commands, on the other hand, are typically validated by the CNC control system for correct syntax and parameters before execution, reducing the risk of errors.

In summary, MDI commands are manually entered commands used for real-time control of CNC machines during manual operation, while G commands are pre-programmed commands used in CNC programs for automatic execution during program execution. MDI commands offer more flexibility and immediate control, but may have higher risks of human errors, while G commands are part of the CNC program and offer more robustness and error checking.