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BACnet Insight

Single Pair Ethernet Meets BACnet:

Bringing IP to the Field Level

Single Pair Ethernet trifft BACnet:

IP bis in die Feldebene bringen

Single Pair Ethernet (SPE) has the potential to signifi- Ethernet over a Single Pair of Wires From this perspective, the step from BACnet over conven-
cantly simplify communication architectures in buil- tional Ethernet to BACnet over Single Pair Ethernet is rela-
ding automation. The technology combines long trans- The name describes the basic principle: SPE transmits tively small. The first solutions are already available on the
mission distances with the possibilities offered by Ethernet over just one twisted pair of wires. For build- market, including controllers equipped with SPE interfaces
end-to-end Ethernet and IP communication. Together ing automation, 10BASE-T1L is particularly interesting. for BACnet applications. SPE and BACnet are therefore
with BACnet, this creates an interesting perspective: a The standardized physical layer supports data rates of 10 no longer a purely theoretical combination for the future.
communication infrastructure based on Ethernet and Mbit/s in full-duplex mode and point-to-point connections Practical implementation has already begun.
IP from sensors and actuators through the automation over distances of up to 1,000 meters. Even at this, its
level and up to building management systems. lowest bandwidth tier, SPE already offers a multiple of the The division of roles is clear: SPE is not a new build-
Single Pair Ethernet (SPE) hat das Potenzial, Kom- kBaud-range data rates typical of conventional RS-485- ing automation protocol and does not replace BACnet.
munikationsarchitekturen in der Gebäudeautomation based field devices. SPE provides the physical Ethernet infrastructure, while
deutlich zu vereinfachen. Die Technologie verbindet BACnet continues to define standardized and interoper-
große Übertragungsdistanzen mit den Möglichkeiten This combines characteristics that are particularly attrac- able communication between building automation appli-
einer durchgängigen Ethernet- und IP-Kommunikation. tive for field-level applications: long distances, lean cations. This is precisely why the two technologies com-
Zusammen mit BACnet entsteht daraus eine interes- cabling and, at the same time, the ability to use Ethernet plement each other so well. BACnet does not need to be
sante Perspektive: eine Kommunikationsinfrastruktur and the IP communication based on it. reinvented to use SPE. Instead, established BACnet com-
auf Basis von Ethernet und IP – vom Sensor und Aktor munication gains an additional path into areas of a build-
über die Automationsebene bis hin zu Gebäudema- Sensors, actuators and compact room automation devices ing where Ethernet has previously been difficult to imple-
nagement-Systemen. generally do not require gigabit data rates. What they need ment economically.
is a cost-effective, space-saving and sufficiently power-
The first solutions are already available on the market. ful network connection. SPE should therefore not simply From Field Devices to Building Management
SPE is also particularly interesting for the modernization of be regarded as a smaller version of conventional Ethernet Systems
existing buildings, as existing two-wire cabling may, under cabling. Rather, it is an extension of the Ethernet family for
certain conditions, be reused. This growing alignment is applications where traditional four-pair Ethernet cabling End-to-end Ethernet and IP communication can sig-
now also reflected at the association level: the Single Pair has so far not been the first choice for technical or eco- nificantly simplify the architecture of a building network.
Ethernet System Alliance and the BACnet Interest Group nomic reasons. Where different field buses are currently connected to the
Europe (BIG-EU) have recently agreed on a partnership to IP level through routers and gateways, more and more
work on SPE-based building automation. The development is now supported by a broad indus- devices could in future become direct participants in an
trial ecosystem. The Single Pair Ethernet System Alliance Ethernet infrastructure.
The demands placed on modern building automation sys- brings together numerous companies and cooperates with
tems are increasing. Energy efficiency and sustainability other organizations and associations. This is an important This offers several potential advantages. Protocol tran-
are becoming just as important as comfort, cybersecurity prerequisite for turning a transmission technology into an sitions can be reduced, diagnostics and network man-
and the integration of different building disciplines. At the open, cross-manufacturer and sustainable system for a agement can be standardized, and new devices can be
same time, the number of intelligent sensors, actuators wide range of industries. integrated more easily. Firmware updates and modern
and room automation devices continues to grow. These IP-based security mechanisms can also move closer to
devices are expected not only to provide data but also The Path to BACnet Is Short sensors, actuators and room automation devices. Remov-
to be configurable and updateable and to communicate ing dedicated routers and gateways also eliminates their
securely with higher-level systems. The result is often a For BACnet, the technological step is smaller than it may acquisition cost, time-consuming commissioning effort
heterogeneous communication landscape. Different bus initially appear. Ethernet and IP-based communication and an additional potential point of failure.
systems operate at the field level, while Ethernet and IP have long been established in the BACnet world. BACnet/
dominate at higher levels. Routers, gateways and proto- IP is part of everyday building automation practice, while The vision does not necessarily involve replacing all exist-
col converters connect these different worlds. Single Pair BACnet Secure Connect – BACnet/SC – provides a mod- ing technologies in the short term. SPE can instead pro-
Ethernet opens up a new perspective: Ethernet can reach ern option for secure BACnet communication. vide an additional option for new devices and infrastruc-
deep into the field level using just a single pair of wires. tures. Conventional field buses such as RS485, traditional
SPE does not change the BACnet protocol itself. Instead, it Ethernet and Single Pair Ethernet are therefore likely to
In this way, SPE addresses key requirements of building auto- provides a new physical Ethernet infrastructure. Wherever coexist for a considerable period of time.
mation: reliable, future-proof communication and a simplified Ethernet and IP are available, IP-based BACnet communi-
infrastructure with fewer gateways and protocol converters. cation can in principle also be implemented. In the longer term, however, SPE offers the opportunity

34 BACnet Europe Journal 45 09/26