112 Engineering Partner E/E network management with diagnostic focus for commercial vehicles By Markus Haab, Account Manager Test, Integration & Diagnostics (onboard) Automotive Trucks, Cognizant Mobility GmbH The number of ECUs is constantly increasing in vehicle development for trucks and construction machinery. This is accompanied by challenging communication between the individual ECUs and coordination in network management, which includes devices, components and subsystems from different suppliers. The interaction of different ECUs and their management is an important factor in vehicle development. The CAN bus communication was originally activated conventionally via clamp 15 (ignition) or exceptionally controlled via separate “wake up” lines. Since some ECUs, for example at the drive CAN, still had to be operated after the ignition was switched off, the communication on the CAN bus was decoupled from clamp 15 in a next step to allow an ECU to continue running for a while. The relevant control units received a “wake up” call via clamp 15. High-speed CAN was then stimulated, using a CAN transceiver. Network management is a software mechanism for controlling the pre- and post-run of ECUs as well as the controlled shutdown of parts of the E/E bus system or the entire E/E bus system in the vehicle. Here, conventional ECUs are stimulated by receiving CAN messages and partially network-capable ECUs are stimulated by defined network management “wake up” messages. Furthermore, the network management ensures a controlled transition of all related control units from active mode to bus sleep mode and vice versa. When there is no more communication on the CAN bus, the bus is in an inactive state, which is also referred to as bus sleep mode. A distinction is made between direct and indirect E/E network management as well as centralised and decentralised E/E network management. With direct E/E network management, each control unit sends an E/E network management-specific message. With indirect E/E network management, the application messages contain the signals necessary for the state change. With central E/E network management, the transition from active state to bus sleep mode is controlled by a master control unit. With decentralised E/E network management, this function is distributed to individual control units. Image: © JLStock/shutterstock.comcom
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