Modular industrial automation appliance and method for transmitting messages via a backplane bus system of the modular industrial automation appliance

A modular industrial automation appliance comprising:

• a backplane bus system;
• a plurality of functional modules connected to the backplane bus system, each of the functional modules comprising:
• a communication network adapter which connects to a respective separate IP subnetwork which is external to each of the plurality of functional modules;
• a functional unit for implementing a communication protocol stack;
• and
• a bridge element linked to the communication network adapter and having a first service access point for the functional unit for implementing the communication protocol stack and a second service access point associated with the backplane bus system, the communication protocol stacks of the functional modules comprising transport functions, and wherein routing functions being excepted from the communication protocol stacks of the functional modules;
• and
• a router module connected to the backplane bus system and comprising:
• a communication network adapter which connects to a respective separate IP subnetwork which is external to the router module;
• a functional unit for implementing a router communication protocol stack, the functional unit being linked to the communication network adapter;
• and
• for each functional module a respective virtual communication network adapter that links the functional unit for implementing the router communication protocol stack to the second service access point of the respective functional module via the backplane bus system;
• wherein only the communication protocol stack of the router module comprises routing functions.