The time required for the processor to scan all I/O modules, writing output data and reading input data. For local I/O, the I/O scan is typically in sequence with the programme scan, in one overall scanning sequence. For remote I/O, the I/O scan is separate from the programme scan; it is either left asynchronous to the programme scan or is synchronised to the programme scan by buffering input data from the I/O scan to write it into the input image table only immediately before the start of each programme scan.