The difference between online and offline PLC programming is . . .where the edited program resideswhether the programming PC has internet connectivitythe type of programming cable usedwhether the PLC is running or stopped

The difference between online and offline PLC (Programmable Logic Controller) programming primarily lies in where the edited program resides.

1. Online PLC Programming: In online programming, the edited program resides in the PLC itself. The programmer makes changes directly to the PLC while it is running. This is typically done when the system is operational and there is a need to make real-time adjustments. The programming PC is connected to the PLC, usually via a programming cable, and any changes made are immediately reflected in the PLC's operation.

2. Offline PLC Programming: In offline programming, the edited program resides on the programming PC. The programmer makes changes to the program on the PC, and these changes are not immediately reflected in the PLC's operation. Once the changes are complete and tested, the updated program is then downloaded to the PLC. This is typically done when the system is not operational or when major changes are being made that require extensive testing before being implemented.

The type of programming cable used and whether the PLC is running or stopped do not fundamentally differentiate online and offline programming. Also, whether the programming PC has internet connectivity is not a defining difference between online and offline PLC programming. The term "online" in this context refers to the direct connection between the PC and the PLC, not to an internet connection.