Designing a Signal Conversion Circuit Board between CAN bus and Modbus for Automated People Mover

DOI: 10.14416/j.ind.tech.2024.12.006

Abstract

The Automated People Mover (APM) is a fully automated mass transit system commonly used for transporting passengers between terminal buildings and boarding gates. This system can be controlled both from within the vehicle and from a control station, with the station being required to continuously monitor the vehicle’s operational status. Research on the design and development of automated people movers in Thailand, including the development of training kits to simulate the operation of APMs, often utilizes infrastructure based on electric buses, which use the CAN bus communication protocol. Meanwhile, station communications typically use the Modbus protocol, a standard in industrial automation. To link the operations between these two protocols, an intermediary connector is necessary. This research focuses on the development of a board for converting communication signals between Modbus RTU and CAN bus using the SAE J1939 protocol. This board, called CAN2RS485, allows users to set the CAN ID as desired, and to configure data from a selected CAN ID to be sent to the Modbus registers for displaying the APM’s operational status at the station. Additionally, it can receive data from Modbus registers and send it to CAN bus to control the operation of the APM. In the Modbus section, the board can also be configured to operate in either master or slave mode as needed.