Ethernet – ISO 13400

For several years now, the Ethernet interface, familiar from network technology, has been increasingly used in vehicle diagnostics. Due to its widespread adoption, numerous hardware components are available in various performance classes and continuously updated versions. This makes it possible to implement diagnostic systems cost-effectively and integrate them easily into existing IT infrastructures.

In addition, thanks to its improved physical characteristics compared to the CAN bus, the interface is also well-suited for larger amounts of data, such as those generated when flashing complex ECUs. This could include, for example, map data for a navigation system, which can easily run into the gigabyte range.

While Ethernet itself is specified by established network standards, its use in vehicle diagnostics is in combination with the DoIP (Diagnostics over Internet Protocol) protocol, which is standardized in ISO 13400. DoIP enables the transmission of diagnostic data over Ethernet and thus forms the basis for modern diagnostic and flash applications in vehicles.

One of the first specifications for the Ethernet interface in the automotive sector was the Open Alliance BroadR-Reach specification. It defines data transmission over an unshielded cable with a twisted-pair wire, also known as One-Pair Ethernet (OPEN). This technology thus helps reduce the cost and weight of the wiring. Standard Ethernet (100BASE-TX), on the other hand, uses at least two data pairs.

As the technology evolved, the BroadR-Reach standard was adopted by the 100BASE-T1 standard (data rate of 100 Mbit/s). This standard, created specifically for the automotive sector, uses superposition and special encoding and scrambling techniques to achieve better EMI performance.