System and method for synchronising a data processing network

A data processing system according to the invention comprising a group of at least a first and a second module, wherein each module has a data processing facility, a clock for timing data transmissions from the module to another module, a time-slot counter for counting a number of time slots which are available for transmission of data. The modules have a first operational state wherein the counted number of time slots is less than or equal to a predetermined number, in which operational state data transmission is enabled, and a second operational state wherein the number is in excess of the predetermined number, in which second operational state data transmission is disabled, Each module has a notifying facility for notifying when it is in the second operational state. The data processing system has at least one detecting facility that detects whether the other modules have notified that they are in the second operational state and the modules each have an initialization facility for resetting the time-slot counter when the module is in the second operational state and each of the other modules has notified that it is in the second operational state.