How to Deliver Robust Smart City Connections Using Single-Pair Ethernet

We’ve all seen how smart cities rely on a robust network of sensors to monitor traffic, air quality, and other services. The resulting data streams are then analyzed to gain vital insights into infrastructure usage, enabling better management of services, resources, and energy to enhance convenience, safety, and efficiency.

Foundational to these networks are data communications technologies such as single-pair Ethernet (SPE) that streamline connectivity and reduce infrastructure requirements for smart city designers. However, harsh environmental conditions can threaten connection reliability where SPE lines are most exposed: at the endpoint. Let’s look at SPE and how Bulgin supports uninterrupted IP communication for more reliable connectivity.

How SPE streamlines device connectivity

Unlike traditional Ethernet, which uses two or four twisted pairs, SPE uses just one pair, enabling the use of lightweight cables that reduce infrastructure costs. Nevertheless, SPE can still carry both data and power over a single line, making it ideal for smart city infrastructure such as security cameras.

Another advantage of SPE is that it supports standard Ethernet protocols such as PROFINET, EtherNet/IP, OPC UA, and Modbus TCP, allowing sensors to connect directly to wider networks and the cloud without requiring a gateway for protocol conversion. By leveraging standards such as 10BASE-T1L (IEEE 802.3cg-2014), which provides a fixed 10 megabit per second (Mbit/s) speed at distances up to 1 kilometer (km), the number of gateways can be further reduced, lowering deployment costs and decluttering networks while maintaining consistent, full-duplex communication.

This is a big win for simplifying the process of building a smart city, but no matter the cable length, you must ensure the connections at each end are highly reliable. This reliability requires that exposed endpoints, such as streetlights, traffic sensors, and parking infrastructure, be resistant to water, dust, and tampering.

A robust solution to SPE connections

To address these challenges, Bulgin’s 4000 series offers an innovative SPE connector design that meets IP66, IP68, and IP69K ratings when mated, providing dust-tight sealing and resistance to high-pressure, high-temperature washdown. Whether operating in adverse weather conditions or being subjected to manual or automated cleaning equipment, the connectors remain safe and secure thanks to a tamper-proof, quick-twist bayonet locking system that surrounds the central SPE port. For coastal cities, the 4000 series is also compliant with EN60068-2-52 for high durability against salt mist, and an operating temperature from -40 to 80°C ensures these connectors can handle widely varying seasonal conditions.

With current and voltage ratings of 4 amperes (A) and 60 volts DC (VDC), respectively, these solutions offer robust electrical characteristics to support Power over Data Line (PoDL) and to streamline smart city infrastructure deployment. A shielded, dual-conductor design also supports high signal integrity in electromagnetically noisy applications such as electric vehicle (EV) charging stations.

The 4000 series includes several cable assemblies available in lengths of 1, 2, 3, or 5 meters (m) with wire gauges of 22 or 26 AWG for flexibility. Three termination options support patching SPE connections into many smart city applications.

For example, the PXPSPE4030/1M/22 (Figure 1) is a 1 m, 22 AWG assembly that features single-ended Bulgin SPE Buccaneer and T1 SPE connector terminations for flexible integration. This solution is well-suited for making short, in-cabinet connections between control boxes and nearby sensors.

Figure 1: The PXPSPE4030/1M/22 cable assembly features single-ended Bulgin SPE Buccaneer and T1 SPE connector terminations for flexible integration. (Image source: Bulgin)

Alternatively, the PXPSPE4031/3M/22 (Figure 2) features a double-ended design that offers the full durability benefits of the 4000 series at both ends of the cable. As a sealed, 3 m, 22 AWG solution, this medium-length assembly is ideal for connecting outdoor devices such as CCTV cameras to switches or wireless access points.

Figure 2: With double-ended SPE Buccaneer terminations, the PXPSPE4031/3M/22 cable assembly supports robust connections between sealed enclosures. (Image source: Bulgin)

Bulgin also provides products such as the PXPSPE4034/5M/26, which features a wire-ended termination for direct connection to terminal blocks. With a length of 5 m and the thinner 26 AWG cable option, this termination offers a discreet solution for connecting existing infrastructure to sealed smart sensors at a distance, for use cases such as air quality monitoring in an HVAC system.

Panel-mounted connectors, such as the PXPSPE4032 (Figure 3), complete the ecosystem and are compatible with all PXPSPE403X cable assemblies. Standard T1 SPE cables can also be used on either side, though this will negate the high ingress protection.

Figure 3: Panel-mount connectors such as the PXPSPE4032 are compatible with all PXPSPE403X cable assemblies. (Image source: Bulgin)

Conclusion

While SPE simplifies smart city deployments, the Bulgin 4000 series offers a flexible ecosystem for implementing reliable SPE connections, especially for exposed endpoints where ruggedness is essential.