Latency evaluation in a Bluetooth-CAN dual media sensor network

In this paper, a system is described which implements the communication between a controller area network (CAN) bus and wireless Bluetooth (BT) networks. The importance of such a system stems from the widespread use of CAN in industrial automation and the growing interest for deploying wireless sensor and actuator networks at the same environment. CAN is known for its robustness and reliability while wireless networks drastically reduce costs and the efforts of installation and configuration. Among the many wireless network technologies available at this date, Bluetooth is neither the fastest nor the cheapest solution, but it complies with the requirements of robustness that industrial applications impose. The developed system forms a data communication environment that comprises two distinct networks, which are interconnected by a bridge-like structure that allows data from sensors that are connected to a CAN bus to be available at the BT network and vice-versa. The latencies due to the interaction between the two different protocols were identified and studied in order to implement a reliable, efficient and satisfactory network of sensors and actuators. Measurement results from an experimental implementation of the system is presented and discussed. An important conclusion from the obtained results is that for high baud rates, average latency is less than 10ms and jitter is less than 2ms, thus showing that the dual media network is a competitive solution for industrial automation.