Updating the Process Image
During cyclic program processing by the CPU, the process image is updated automatically. With the S7-400 CPUs and the CPU 318 you can deselect the update of the process image if you want to:
• Access the I/O directly instead or
• Update one or more process image input or output sections at a different point in the program using system functions SFC26 UPDAT_PI and SFC27 UPDAT_PO.
