Program scan

The program scan is the portion of the overall cycle where Ladder Logic instructions of the user's application software are executed. Here, the embedded firmware program operates on the portions of memory (E2PROM/FLASH/RAM) that have been loaded previously with the application software from the binary file.

Program files contain the actual instructions to be executed. Data files are used to maintain program variables and other data structures required by the logic. It is the responsibility of the firmware program to properly decode and execute instructions in the program files. The program must also properly update the contents of the data files based on these instructions.