Open the PLC editor and check if the PLC has a program added in the task mapping.
When debugging while selecting between multiple PLCs
it happens in the IDE versions of the 2.4.0.x series that the selected controller is not saved in the position of the selected controller for debugging (the Controller field is empty). Therefore, their values are not displayed for variables, see:
In order for the values to be displayed, it is necessary to manually select the controller again, this time while the tuning is running.
This bug occurs on the IDE side and will be fixed with another version series.
If this problem affects local variables, function blocks, inputs and outputs (not global variables), make sure that the name of your program does not begin with a number. If the program starts with a number, rename the program and map it again. This problem occurs in versions of the Merbon IDE earlier than v2.4.0.x.
Make sure the name of this program does not begin with a number. If the program starts with a number, back up your project and rename the program name with the .scu extension in the File explorer. Then open your solution and delete programs from the project that start with a number and add already renamed programs to the solution. After compiling the project, map the programs to the PLC again and upload the solution to the PLC.