Design of Cloud-based IoT Gateway for CAN Bus to Modbus RTU Integration

Abstract

The CAN (Controller Area Network) and Modbus RTU protocols are both popular standards and have long been widely used in industrial systems. There are some difficulties and challenges in data exchange and interoperability between devices that use different communication networks and protocols. These traditional technologies should also be applied with cloud migration in the era of advanced IIoT and Industry 4.0. In this paper, we designed a gateway or data converter to realize the data exchange between CAN and Modbus RTU network. In topology, the gateway serves as a standard CAN node for CAN network and meanwhile as a Modbus RTU slave for serial RS485 network side. We chose the Raspberry Pi as the main component and designed the add-on circuit board with CAN and RS485 communication capabilities. Through the design of intelligent data conversion method and mapping mechanism, all data between CAN network and Modbus RTU are transferred in the memory buffer of Raspberry Pi, which provides CAN data to devices such as PLC or HMI in Modbus RTU network. Theoretically, each manufacturer's unique CAN data protocol can easily be exchanged to Modbus RTU with convenient configuration. The gateway incorporates an embedded web server that allows monitoring and configuring data or parameters via a web browser. Moreover we also have designed some REST APIs at the cloud site, therefore Modbus RTU data mapping from CAN messages is received by IoT platform and specific IoT solution can be developed for organization need. With proposal gateway, any device with CAN interface could be easily integrated into Modbus RTU network with some IoT functions without almost changing hardware or software.