Simply put, single pair Ethernet is a cable configuration that uses one pair of wires (or conductors) to transmit data at speeds of up to 10 Mbps (potentially up to 1 Gb/s in the future). Designed for industrial users, this single-pair cabling can support up to 52 watts of dc power, covering a range of devices that need both power and data at distances up to 1,000 meters.
Single pair Ethernet also provides reliable power (versus wireless) to sensors that are fixed to a physical location and may not have their own power source.
Single pair Ethernet is also referred to in the standards as “twisted pair.” That nomenclature refers to the fact that a single pair consists of a balanced pair of conductors, each carrying a different signal. The most common configuration is a twisting of the two wires as shown in the image above.
Single pair Ethernet was designed to meet the specific needs of industrial manufacturing users, who are operations technology (OT) professionals concerned with connecting low-speed devices such as sensors, actuators, and relays, as well as access control and lighting applications.
For their use case, OT professionals wanted a simpler, low-cost and space-efficient alternative to the shrieking-fast, 4-pair cabling construction that has become the dominant networking technology in office, telecom, and data centers. Since for technical reasons one wire isn’t reliable, a single pair of wires is the simplest, most compact configuration.
OT professionals also needed features that were complementary to their specific use case, where data often travels long distances to sensors, actuators, and other types of connected devices commonly found on the factory floor.
They also wanted cabling that could be easily retrofit within an existing facility. From a space perspective, single pair Ethernet easily replaces existing two-wire systems and is compatible with the terminal block-style connections typically found in industrial applications.
Quite possibly the most important benefit of single pair Ethernet is that it is a familiar protocol stack, well known by most of the world. The end-to-end industrial Ethernet network provided by single pair Ethernet eliminates the need for a slew of proprietary protocols that run on various fieldbuses.