A Multiplex Protocol for Medium Scale Systems

For a self-running decentralized bus network, the CSMA-CD (Collision Detection) approach has been suggested, however one of the drawbacks with such an approach is the high cost incurred due to the large amount of hardware required for implementation.

We have investigated a medium scale system utilizing Collision Avoidance CSMA transmission method. Evaluation boards were then constructed and tested. With 16 nodes operating at 62.5Kbaud, it was confirmed that for each node transmitting 2 bytes of data, an access time of approximately 17ms was achievable. Furthermore, we have considered the effects of EMC when equipped within a wiring harness.