Patent ID: 8464056

Claim:
A communication method for transmission of time-triggered (TT) ethernet messages over a distributed real-time system, comprising a plurality of node computers, whereby each node computer is provided with at least one ethernet controller that is directly connected via a data line to a port on a TT Ethernet (TTE) star coupler that is uniquely assigned to one of the node computers, and whereby multiple TTE star couplers are connected directly or indirectly to one another via one or more data lines to form a TTE network, wherein a TTE message scheduler dynamically calculates conflict-free schedules for a number of time-controlled messages and signs the schedule designated for each node with the private portion of a public key signature before it sends this schedule to the corresponding node computer, and whereby the signed periodic schedule that is sent by the TTE message scheduler to the node computer in the form of a TTE message header in an event-triggered ethernet (ETE) message is incorporated by each node computer into each dynamically calculated TTE message, and whereby the TTE star coupler checks whether each dynamically calculated TTE message contains an authentically signed schedule: wherein the conflict-free schedule is signed with a simple symmetrical key before this schedule is sent to the corresponding node computer, and whereby each node computer incorporates the signed periodic schedule of the TTE message header into each dynamically calculated TTE message, and whereby the TTE star coupler checks whether each dynamically calculated TTE message contains an authentically signed schedule; wherein all star couplers include a configuration message from a service node that contains the following: sending time point for the message, current schedule version, starting time point for the validity of the current schedule version, subsequent schedule version, starting time point for the validity of the subsequent schedule version, current public key for checking the scheduler signature of a TTE message, and the connection structure of the TTE star coupler, whereby the message content is secured through the electronic signature of the TIE message scheduler; wherein the service nodes modify the key used in the calculation of TTE header during operation; and wherein each star coupler is notified of the public key of the TTE service node a priori over a secure channel.