Your question is CAN Interface Between Simulation and ECU. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain how you would design a communication interface between a high-level simulation node and a physical vehicle ECU over CAN bus.
Address the application-level code structure rather than CAN electrical design. Explain how you would represent messages and signals, isolate the CAN driver, handle timing and failures, inject dependencies for testing, and expose ECU state to the simulation node. Include the dependency direction between layers, one representative message flow, and the trade-offs behind your design.