A MODBUS/SLLDN gateway implementation for interfacing WSANs to SCADA systems

MODBUS is still one of the most widespread application layer protocols used in industrial communication due to its simple request-response communication session and its readiness to be implemented on top of several lower level communication protocols and various physical media such as RS232/RS485 serial lines and Ethernet TCP/IP. Given the well-known inclination of Modbus to inter-networking, a solution to connect a wireless sensor and actuator network (WSAN) based on the PHY layer as defined by IEEE 802.15.4 and one of the MAC behaviour modes proposed by the IEEE 802.15.4 amendment to SCADA applications is investigated in this paper. A simple low latency deterministic network (SLLDN) and a MODBUS/SLLDN gateway were implemented to have a WSAN interfaced to a NI Lookout SCADA server application for data acquisition and control using its built-in MODBUS serial driver.