Patent ID: 7184449

Claim:
A method to perform a cycle synchronization between interconnected sub-networks, in which a reference node connected to one of the sub-networks transmits a respective cycle time information to cycle masters of all other sub-networks at recurring time instants, and the cycle masters of all other sub-networks adjust their cycle time accordingly, an adjustment of the cycle time within a cycle master is performed by the following steps: determining a first time interval (Δt 1 , Δt 1 ′) in-between two receptions of cycle time information from the reference node with an own clock; determining a second time interval (Δt 2 , Δt 2 ′) in-between two corresponding transmissions of cycle time information from the reference node based on the received cycle time information; comparing the first time interval (Δt 1 , Δt 1 ′) and the second time interval (Δt 2 , Δt 2 ′); and adjusting the own cycle length according to the comparison result.