Which is “better”? BACnet, LonWorks, Modbus, or KNX

BACnet, LonWorks, Modbus, or KNX which is better
Weighing the most popular building network protocols against each other

BACnet gets compared to a lot of other protocols on the market, including LonWorks, Modbus, and KNX. In this article, we break down the advantages and disadvantages of each protocol. Be sure to check out our articles on each of the protocols: LonWorks, Modbus, KNX, and a few reasons we think you should adopt BACnet

There have been industry debates for years now about which protocol is “better”: BACnet, Modbus, KNX, or LonWorks. Many argue that BACnet is the clear victor, although there are still those out there who carry a torch for Lon and Modbus. And, while KNX has largely been discounted because of its more limited North American reach, it has a strong presence in Europe. 

Now, it’s important to remember these protocols are used in very different applications. There are a variety of reasons to use them, and they can be deployed together on the same building networks. So really, debating which one’s “better” is futile. At their core, they’re simply different. 

All the same, it’s important to understand these protocols individually. We’ve made a table to help clarify some key distinctions:

 

BACnet

LonWorks

Modbus

KNX

Device Types

Go-to protocol in HVAC and mechanical; growing into lighting and security.

Security, lighting, HVAC, metering, and the like.

Traditionally for industrial systems, transport, and energy.

All sorts of systems including HVAC, access control, sensors, security, and lighting.

Markets

Dominant in commercial buildings, especially campuses. Often interworked with Modbus and LonWorks.

Mostly present in commercial buildings, and somewhat on campuses. Often interworked with other protocols.

Mostly present in commercial buildings, and somewhat on campuses. Often interworked with other protocols.

Mostly present in commercial and residential building automation.

Pros

Testing and certification process; Open protocol; User-friendly; Widely adopted; BACnet Web Services lends itself to IoT; Single pane of glass solution; BACnet/IP is built for the future

Testing and certification process; Proprietary, but can be interworked; Was developed as (1) a data protocol and (2) an electrical standard for digital communications

Testing and certification process; Open protocol, with no fees or charges required; De facto protocol in industrial applications; Easy to use/understand; Can easily be used over the Internet

Testing and certification process; Open protocol, that’s easy to interwork; Works on different transmission types; Decentralized topology; Low energy consumption

Cons

Some customers complain about network issues like broadcasts and MS/TP chain problems; The open protocol means many users must manage several different vendors on one site.

Critics say it’s an outdated protocol that’s been outpaced by open, more modern protocols; LonWorks has a lower adoption compared to BACnet, so there’s not the same community of support.

Often customers have no choice to use or not use Modbus: the hardware constraints just require it; Widespread adoption of Modbus means not all installations have necessarily been certified.

KNX is not widely adopted outside of Europe. That means there just isn’t the same community that there is for other, more widely adopted protocols.

Setra also has a useful table demonstrating some of the key differences between BACnet, LonWorks, and Modbus. 

At the end of the day, protocols have to be chosen on a somewhat case-by-case basis. And not all protocol implementation is equal: devices from various vendors can have more features or fewer, great capabilities or less. Each installation will also be better or worse in different ways depending on the building or system’s needs. But internetworking between protocols is standard, and together they form a truly interoperable system.

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