Networking Fan Coil Controller for HVAC Systems

In contrast to conventional standalone fan coil unit (FCU) that serves a designated conditioning zone, the networking fan coil controller (NFCC), investigated in this paper, is designed for air conditioning installed in spaces of medium to large size. With an architecture that separates user interface panel from the embedded control core, the proposed NFCC is able to control up to 255 ceiling mounted fan coil unit modules through Modbus network by just one wall mounted user interface module. In this regard, this paper addresses the following three issues: (1) the design of the underlined communication protocol employed between ceiling modules and the wall module; (2) the implementation issues relating to storage and packaging of setting parameters; broadcast and unicast communication modes; and (3) the communication enabling technique for master/slave architecture design. Operational scenarios that detail phases of initialization, normal control setting in groups, and selected ceiling module, are included to demonstrate the feasibility of the proposed networking fan coil unit