Design, Verification, and Performance of a MODBUS-CAN Adaptation Layer

The MODBUS protocol is nowadays very popular at both the field and SCADA levels, thanks to its simplicity and its open nature. However, the choice of physical transmission medium is currently limited to either the low-performance TIA/EIA-485 bus (MODBUS RTU) or Ethernet (MODBUS TCP), with its topology and cabling shortcomings and additional software complexity. In this paper, a MODBUS adaptation layer for the Controller Area Network (called MODBUS CAN) is proposed, formally verified, and evaluated experimentally. The results show that, on a typical low-cost embedded system, its performance compares favorably with respect to a MODBUS TCP implementation, based on a 100Mbps Ethernet, carried out on the same system and using the same protocol stack.