Abstract: A method of supplying (1419, 1420) instructions to operational stations to operational stations (1501, 1502) is disclosed. Operations to be performed at said operational stations are defined as a graphical data floe diagram (1401). The data flow diagram is converted into sets of system description data. A respective set of instructions is downloaded to each of the operational stations. At each operational, station instructions are parsed to populate a data table (1503) and an event table (1504). The execution of events is scheduled in accordance with predetermined priority definitions and the events are executed in accordance with the scheduling step.