Ethernet has become a mainstream communications protocol and sits atop the control pyramid in building automation. Recently, the Institute of Electrical and Electronics Engineers (IEEE) defined an Ethernet standard, IEEE 802.3.cg, for 10 Mb/s operation and associated power delivery over a single balanced pair of conductors. Because a single-pair cable can now support both data and power, adoption of the standard can lead to significant cost savings and easier installation in building automation applications.
There are numerous efforts to take Ethernet to edge devices. Multiple communication networks currently exist in building automation—for example, heating, ventilation, and air-conditioning (HVAC) applications use Modbus; access control uses BACnet; lighting uses LonWorks; and fire safety uses Ethernet. This fragmentation of networks requires gateways to perform protocol conversion to unite networks at the top of the building automation control pyramid. End users must in turn manage complex systems.