Experimental evaluation of bandwidth allocation for the master-slave/token-passing protocol

Digital communication networks are a core technology in advanced building automation systems. Building automation and control network (BACnet), a data communication protocol designed specifically for building automation and control systems, uses the master-slave/token-passing (MS/TP) protocol as one of its field-level networks. Previously, the authors introduced a basic concept of bandwidth allocation for MS/TP to improve its real-time communication capability. In this study, the authors developed a communication module that implements the proposed scheme, and used it in an experimental model to examine the validity of the bandwidth allocation scheme for MS/TP. Experimental results show that the modified MS/TP protocol satisfies the requirements for real-time communications using cyclic and life-safety messages in BACnet communication services.