What is typically not allowed in PLC Program mode?

In PLC Program mode, the primary purpose is to make changes and modifications to the project files, which include editing the ladder logic and configuring the overall project settings. Executing the ladder program during program mode is not typically allowed, as this mode is intended for development and testing rather than live execution. Running the program requires the PLC to be in Run mode, where it can execute the instructions and control the process as intended.

This distinction is essential because executing a program while editing could lead to unintended consequences and conflicts, as changes made could be in flux while the system is up and running. Therefore, PLC systems are designed to restrict execution of the program in this mode to ensure stability and reliability while the programmer is working on the logic.