Monitoring/Debugging the Safety PLC
The project execution on the Safety PLC (or simulation) can be monitored while PLCnext Engineer is in monitoring mode or in debug mode, i.e., if PLCnext Engineer is attached to the application process running on the Safety PLC. In monitoring and in debug mode, online values are read cyclically from the Safety PLC and displayed in the editors. Debug mode additionally allows to execute debug commands.
The monitoring mode and the debug mode support you during the function test: they enable checking the behavior of the input and output devices, thus detecting programming errors and ensuring that the project is executed correctly and as intended. In monitoring mode and debug mode, the project cannot be edited.
In monitoring and debug mode, the Safety PLC icon in the PLANT and in the ONLINE STATE window indicates the Safety PLC status. See topic "Safety PLC States" for details. Additionally, the editor group tabs are marked by a triangle in the upper left corner:
Difference between monitoring mode and debug mode
Monitoring mode allows read-only access to the Safety PLC by transferring online values from the Safety PLC to PLCnext Engineer. Therefore, monitoring mode is considered as safety-related mode as the execution of the application cannot be influenced by debug commands.
Debug mode additionally allows write access to the Safety PLC by providing commands for starting/stopping the program execution as well as debug commands. Therefore, debug mode is considered as non-safety-related mode as the execution of the application can be influenced.
What do you want to do?
- Activate and use the monitoring mode to display online values
- Activate and use the debug mode to start/stop the program execution, display online values, and force/overwrite variables
- Activate and use the debug mode to execute Single Cycle Operation of the Safety PLC
- Use the WATCHES window in monitoring mode and debug mode