Issue link: https://www.e-digitaleditions.com/i/1347119
April/May/June 2021 I 11 Single-pair Ethernet supercharges the customer-driven expansion of Ethernet adoption by significantly reducing the size and cost of applying Ethernet to edge devices. While larger gauge cables are required to bring SPE to its full one kilometer reach, the more typical 23 AWG twisted-pair cabling is expected to be standardized to provide 400 meter reach, sufficient for many applications. Reducing pairs reduces copper usage and will have a significant impact on cost. Reducing pairs on the system also substantially reduces the complexity of the electronics required to connect the medium dependent interface (MDI) safely and reliably to the physical layer interface (PHY), thereby reducing the complexity of the power over data line (PoDL) variant of PoE. This provides better options for miniaturization and cost reduction of edge devices, while still using Ethernet TCP/IP to communicate. Accessing a fieldbus system for the first time can be intimidating. There is a transition that is required over the next 20 years between the current and future generations of workers that build and support automated systems. Therefore, a lot of learning needs to happen, ranging from protocol translation to how to make sure polarity is not switched for the fieldbus on the screw terminals. With SPE, installation can be simplified as well as moves, adds, and changes (MACs) to the system with FIGURE 5: Representative IP20 connector for SPE. FIGURE 6: Representative IP67 connector for SPE. Single-pair Ethernet supports 10 Mb/s of bandwidth to the edge device over its one kilometer reach. simple connectivity instead of screw terminals or cage clamps. Simply strip the outer jacket, position into the connector, and snap close. This creates a reliable and repeatable termination reminiscent of terminating an Ethernet jack, yet it is far easier and faster because of connecting only a single pair. Connectivity for SPE provides several possible options, and industry standardization efforts continue to make progress. For IP20 applications, IEC and TIA have standardized on the IEC 63171-1 interface, which uses the proven small size form factor LC optical fiber connector that includes two copper pins. This con- nector is very robust and has been tested to perform in high electromagnetic interference (EMI) environments that are common to industrial control panels, as well as some building automation applications (Figure 5). Most IP67 applications are more difficult since there are a breadth of applications and needs for sensors and other devices. The process industry, which is the first mover on 10 Mb/s over SPE, has adopted the A-Code M8 connector that allows IP65 or better sealing and a standardized 4-pin interface (Figure 6). There are several other options in the industry being considered using new connector designs; standardization through four key industrial fieldbus vendor organizations should settle what the preferred interface will be.