A communication architecture of a train in which at least one central processing unit arranged in a train carriage is interconnected through a communication network of the train with a plurality of peripheral processing units. The central processing unit is provided on a single board with: a processor designed to process data associated with an SIL 0 safety level; a coprocessor designed to process data associated with an SIL 1-SIL 2 safety level; an internal bus built on the board and configured to allow a two-way data communication between the processor and the coprocessor; an interface for the communication network of the train. The coprocessor is designed to be programmed in a reconfigurable manner with a software that allows the validation and encoding of data coming from the processor according to a safety protocol.