Extension element for a device in a bus network

A method for communication in a network of devices, mutually connected via a first and second communication cable, in which said network has a linear bus topology, said method comprising:

• providing an extension element for each of said devices, comprising:
• a first, second and third connection point,
• a switch connected to said first and second connection point,
• a processing unit connected to said third connection point, and to said first and second connection point over a connection which does not comprise said switch,
• a first and a second interface adapted for data exchange between said first respectively second connection point and said processing unit;
• a read-write connection between the read port of said first interface and the write port of said second interface, and a write-read connection between the write port of said first interface and the read port of said second interface,
• connecting said first respectively second connection point to said first second communication cable;
• connecting said third connection point to a control unit comprised in each of said devices;
• controlling said network in bus mode by closing said switch by said processing unit to form a direct connection between said first and second connection point, which forms part of the common bus of said network;
• controlling said network in serial mode by opening said switch by said processing unit to break said direct connection;
• in said serial mode, changing the status of said extension element from an idle status, wherein no data traffic is possible over said read-write and write-read connection, to a forward status, wherein data traffic is possible over said read-write or write-read connection, by said processing unit changing the impedance in said read-write connection and/or in said write-read connection and/or in a connection between said first and second interface via said processing unit.