Hardware Connection Protocols

Hardware Connection Protocols

CAN - Controller Area Network

A vehicle bus standard, covers part of the physical layer, the datalink layer, and could also extend to higher layers as well in the OSI network model. It’s a protocol used for communication between ECUs.

  1. Bus-based: two-wire bus. Works by broadcasting and devices judge whether a message is relevant.
  2. Using a CAN interface device, we can write LabVIEW applications to communicate with a CAN network.

UDS - Unified Diagnostic Services

UDS is an international diagnostic communication protocol used in electronic control units(ECUs) within automotive electronics. It’s a protocol used between diagnostic testers and the ECUs.

  1. Client-Server architecture. Clients are the tester tools and the servers are the vehicle ECUs.
  2. Extends to Application layer in OSI 7-layer model.

CAN vs UDS

  1. CAN is used for communication between ECUs, while UDS is used for communication between a diagnostic tester and an ECU
  2. CAN is a low-level protocol used for real-time communication, while UDS is a higher-level protocol used for diagnostic purposes.
  3. CAN is faster than UDS, as it is designed for real-time communication. UDS, on the other hand, is designed for slower, more controlled communication between the diagnostic tester and the ECU.

PLC

Originated in the late 1960s in the automotive industry in the US. It is basically a computer designed to work reliably in harsh environments. It consists of:

  1. Process unit(CPU).
  2. Power supply unit which convert AC voltage to DC.
  3. Non-volatile memory.
  4. Input and output interface.
  5. Communication interface to exchange data with other PLCs/Modules.

Many PLCs have a real-time operating system(RTOS) -> determinism is an important property for RTOS. Processing time requirements need to be fully understood and bound rather than just kept as a minimum compared to time-sharing operating system.

Comparing it with the traditional PC:

  1. It’s ruggedized, designed to be reliable in harsh environments and conditions, such as strong vibrations, extreme temperatures and wet or dusty environments.
  2. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory.
  3. Usually output results must babe produces in response to input within a limited time.
· Hardware