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Passenger cars are equipped with an OBD connector according to SAE J1962 / ISO 15031-3. Passenger cars that support ISO UDS on DoIP use the same connector with Ethernet pins according to ISO/DIS 13400-4 (Ethernet diagnostic connector). If external test equipment is connected to the Ethernet diagnostic connector via a 100BASE-TX cable with the RJ45 connector at the tester, a VCI is not necessary anymore. With a device that fits the Ethernet diagnostic connector physically and acts as a converter between the Ethernet signals and WLAN, external test equipment that supports wireless communication, can be connected to the vehicle. Examples for such wireless external test equipment include Android/iOS- based smart phones and tablets with purpose-made applications (APPs). The software components of external test equipment are standardized in ISO 22900 (MVCI). The MVCI D-Server processes data in ODX (ISO 22901) and sequences in OTX (ISO 13209).

SAE J1939 is the synonym for a CAN-based in-vehicle network for heavy-duty road-vehicles (trucks and buses) and non-road mobile machinery (NRMM). The SAE J1939 standards collection consists of 18 parts and 2 digital annexes. SAE J1939-21 (Data Link Layer) describes the data link layer using the CAN protocol with 29-bit identifiers, SAE J1939-73 (Application Layer – Diagnostics) includes the specification of diagnostic messages (DMs). The software components of external test equipment can be described by software interfaces (APIs). ISO 22900 (Modular Vehicle Communication Interface) contains the description of the D-Server that comes with the D-Server API for the diagnostic application and the D-PDU API for the connection to the in-vehicle network (e.g. CAN). ISO 22901-2 (D-PDU API) references SAE J1939-73 and SAE J1939-21 as “Truck and Bus CAN”. D-Server based external test equipment is powered by data which is described in ODX.

The increasing complexity of microcontroller-based automotive E/E systems that control road-vehicles and non-road mobile machinery comes with increased self-diagnosis functions and diagnosability via external test equipment (diagnostic tester). Technicians in the development, production and service depend on diagnostic test equipment that is connected to the E/E system and performs diagnostic communication. Examples of use cases of diagnostic communication include but are not limited to condition monitoring, data acquisition, (guided) fault finding and flash programming. More and more functions of a modern vehicle are realized by software (firmware). Powerful multicore servers replace the numerous control units and many control unit functions can be performed directly by smart sensors and actuators. New E/E system architectures come with increased self-diagnostic capabilities.

In the near future, vehicles will operate autonomously and communicate with their environment. This communication includes Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I) communication, and comunication with cloud-based servers (V2C). To improve the resilience of remote diagnostic communication between a vehicle and external test equipment against cyberattacks, it is imperative to understand and analyze the functionality and vulnerability of each communication system component, including the wired and wireless communication channels. This paper serves as a continuation of the SAE Journal publication on measures to prevent unauthorized access to the in-vehicle E/E system [9], explains the components of a cyber-physical system (CPS) for remote diagnostic communication, analyzes their vulnerability against cyberattacks and explains measures to improve the resiliance.

Diagnostic Communication with Road-Vehicles and Non-Road Mobile Machinery examines the communication between a diagnostic tester and E/E systems of road-vehicles and non-road mobile machinery such as agricultural machines and construction equipment. The title also contains the description of E/E systems (control units and in-vehicle networks), the communication protocols (e.g. OBD, J1939 and UDS on CAN / IP), and a glimpse into the near future covering remote, cloud-based diagnostics and cybersecurity threats.