Synchronization of two communication networks of an electronic data-processing system

An electronic data-processing system, comprising:

• a first communication network including one or more respective nodes, a first time schedule being established for the first communication network and defining at least one respective time slot for a respective synchronization message, the respective synchronization message for a selected synchronization message time slot being generated by one of the nodes of the first communication network;
• a second communication networks including one or more respective nodes, a second time schedule being established for the second communication network and defining at least one respective time slot for a respective synchronization message, the respective synchronization message time slots of the two communication networks coinciding;
• a synchronization device configured for providing the respective synchronization message of the second communication network for the selected synchronization message time slot as a function of the respective synchronization message of the first communication network for the selected synchronization message time slot;
• and
• a switch that connects the first communication network to the second communication network, wherein the synchronization device is configured to transfer the switch into a closed state to provide the respective synchronization message of the second communication network for the selected synchronization message time slot when the selected synchronization message time slot of the first communication network is present.