A railway vehicle comprising: - a safety relevant component for safely operating the railway vehicle, such as a traction or a braking unit, said safety relevant component being adapted to provide status data about its operation; - a processing and diagnosing device for controlling said safety relevant component, for receiving and processing said status data and for generating diagnosis data about the condition of the railway vehicle; - a safety relevant data network including a Multifunction Vehicle Bus or MVB interconnecting the safety relevant component and the processing and diagnosing device; - an information Ethernet data network, different from the safety relevant data network, for distributing information data, such as traffic or seat reservation data, inside the railway vehicle, said information Ethernet data network also including a receiving device configured for bidirectional radio communication with a remote back office; - a diagnosis data requests relaying device arranged to interconnect the receiving device and the safety relevant data network, wherein the diagnosis data requests relaying device is a MVB card adapted to relay a request for diagnosis data received by the receiving device from the remote back office to the processing and diagnosing device via the safety relevant data network, the MVB card being only able to send predefined and fixed messages, of which only is a limited number of different ones, to the processing and diagnosing device via the safety relevant data network and including a dedicated physical programming access port which is the only way to reprogram the MVB card; - a transmitting device for sending data from the railway vehicle to said remote back office, said transmitting device being part of the information data network; and - a gateway interconnecting the safety relevant data network and the information data network, wherein said gateway is a unidirectional security gateway, which allows data communication from the safety relevant data network to the information data network and prevents any data communication from the information data network to the safety relevant data network, said gateway being a Field-Programmable Gate Array or FPGA having a dedicated physical FPGA access port which is the only way to reprogram the FPGA, wherein said unidirectional security gateway is adapted to relay said diagnosis data from said processing and diagnosing device to the information data network, and wherein said transmitting device is adapted to send the relayed diagnosis data from the railway vehicle to the remote back office. - a safety relevant component for safely operating the railway vehicle, such as a traction or a braking unit, said safety relevant component being adapted to provide status data about its operation; - a processing and diagnosing device for controlling said safety relevant component, for receiving and processing said status data and for generating diagnosis data about the condition of the railway vehicle; - a safety relevant data network including a Multifunction Vehicle Bus or MVB interconnecting the safety relevant component and the processing and diagnosing device; - an information Ethernet data network, different from the safety relevant data network, for distributing information data, such as traffic or seat reservation data, inside the railway vehicle, said information Ethernet data network also including a receiving device configured for bidirectional radio communication with a remote back office; - a diagnosis data requests relaying device arranged to interconnect the receiving device and the safety relevant data network, wherein the diagnosis data requests relaying device is a MVB card adapted to relay a request for diagnosis data received by the receiving device from the remote back office to the processing and diagnosing device via the safety relevant data network, the MVB card being only able to send predefined and fixed messages, of which only is a limited number of different ones, to the processing and diagnosing device via the safety relevant data network and including a dedicated physical programming access port which is the only way to reprogram the MVB card; - a transmitting device for sending data from the railway vehicle to said remote back office, said transmitting device being part of the information data network; and - a gateway interconnecting the safety relevant data network and the information data network,