This article appeared in Electronic Design and has been published here with permission.

Ethernet has become a mainstream communications protocol, at the top of the control pyramid in building automation. Recently, the Institute of Electrical and Electronics Engineers (IEEE) defined a new 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 the 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 the use of gateways to perform protocol conversion to unite merge networks at the top of the building automation control pyramid. End users must in turn manage complex systems.

Reasons for the existence of various communication networks include the need for longer distances, multidrop connectivity, powering scheme and support for unique protocols. Single-pair Ethernet (SPE) can address many of the above said reasons. Having Ethernet to the edge devices offers benefits such as direct accessibility for the control system, status updates, predictive maintenance, standardized hardware and interoperability across various systems.