US Patent 7149606 Synchronizing controllers linked by a communications network

A control system includes controllers that are coupled mutually by a communications network, on which information, transmitted from a master controller to a slave controller, is used to make timing corrections on the slave controller in order to synchronize event timers on the slave controller with that of the master controller. Timing accuracy for the occurrence of the event commanded by each controller is synchronized in narrow range of time, preferably within a few milliseconds depending on the specific application and system.