Patent ID: 8774162

Claim:
A real time control network system comprising: a plurality of controllers connected through a bus, each of the controllers including a transmission process unit which transmits a frame in every communication cycle with assigning a slot and a reception process unit which receives the frame from the assigned slot, the frame being transmitted and received among the controllers; wherein the communication cycle is counted again from 0 after the communication cycle is counted from 0 to a maximum value; the plurality of controllers includes: at least one reference signal transmission controller having a reference signal generation unit which receives the communication cycle and generates a reference signal, the reference signal acting as a reference for starting transmission of the frame or starting reception of the frame, and a reference signal transmission unit which transmits the reference signal; and at least one reference signal reception controller having a reference signal reception unit which receives the reference signal; each of the controllers further includes a communication cycle update unit which keeps the communication cycle among the plurality of controllers the same, a filtering condition table which has the communication cycle at the time when the transmission process unit starts to transmit or at the time when the reception process unit starts to receive and has the reference signal, and a filtering process unit which compares the reference signal and the communication cycle to the filtering condition table and starts the transmission process unit or the reception process unit when the communication cycle and the reference signal match a condition of the filtering condition table; each of the controllers includes a round value which counts repeating numbers of the communication cycle; the reference signal generation unit includes a round count unit which updates the round value when the communication cycle becomes a maximum value, a command signal condition table which at least has the communication cycle at the time when the transmission process unit starts to transmit or at the time when the reception process unit starts to receive and the round value, and a command signal generation unit which compares the round value and the communication cycle to the filtering condition table and generates a command signal when a condition is matched, the command signal indicating a communication cycle of the frame and an offset from round 0; and the command signal is used as the reference signal.