The functions FC_MAreaRead() and FC_MAreaWrite() allow consistent data exchange between the marker area and a buffer of the program. The copying operation cannot be interrupted. This enables a consistent data exchange between the marker area and variables of the program regardless of the priority of the tasks. A number of bytes, i_udiByteCount, (0...65535), starting with the initial address, i_udiAddr, is read from the marker area (0...65535) and copied to the transferred buffer with the address i_diDestination. The transferred buffer must contain at least i_udiByteCount bytes.