In this mode, program execution is possible, as well as editing and monitoring during operation. This is the most frequently used mode in program development. When this mode has been selected, controller has an obligation to supply a PC with information which relates to program itself, or more precisely to status of variables in the program.
If we additionally confirm Monitoring option from an Online menu, we can follow current values of variables on the monitor itself, in real time. All changes in inputs and outputs can be viewed on the monitor, and status of variables and program locations used in the program are registered and memorized.