Modern trains must provide a certain level of control, diagnostic and information services. To satisfy it, rail vehicles have to be equipped with devices communicating over special networks. Nowadays, commonly used networks are described in the IEC 61375 and the UIC 556 standards.
The National Train Bus (NTB) is a train network standard created in parallel with IEC 61375. The main difference is that it can operate on lower speed than it is common in rail environment, while still keeping the time-critical character of communication in mind.
Therefore, it is suitable for rail vehicles, including refurbished ones, to avoid high requirements on installed hardware and software. It was successfully tested and it is being used in many different DMUs operated by Czech and Finnish Railways.
This article describes the main communication and diagnostic principles of NTB and shows the differences between the IEC 61375 solutions and NTB.