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Control Systems Protocols


One manufacturer touts its protocol of choice as “open”, while another, deploying products that use a very different protocol, likewise declares its products “open”. Yet, their products cannot communicate one with another. What’s the story, here?

What Are Protocols?

By definition, communications protocols are “rules determining the format and transmission of data”. Because a transmission media serves as transport of data, companion hardware rules come into play.  Transmission media include unshielded twisted pairs (UTP), coaxial cables, shielded twisted pairs (STP) and radio waves.

Public vs. Proprietary

Protocols are either in the public domain or are proprietary to a private manufacturer. This discussion covers protocols widely used in building automation and control systems. Moreover, this discussion of necessity incorporates the idea of “open systems”. Open systems do not always feature open protocols, and vice versa.

Protocols in the public domain and deployed in building control systems include



Lon Mark

Sedona Framework


Which protocol does Rockwall Controls favor? We are “protocol ambivalent”, but we are passionate about “open systems”. It’s all a matter of which combination of products results in the best, most reliable “open system”.

What Makes A System Open?

Control systems products, hardware and software, manufactured to communicate via one or more public protocols AND distributed through an unrestricted open marketplace describe “open systems”.

Numerous manufacturers ship products that use open protocols, but sell through franchised contractors.  An atmosphere of competition exists naturally between contractors. The franchisee depends on his/her proprietary advantage and, therefore, suspiciously guards his/her marketplace. Therefore, a franchise holder most often will refuse to sell product to his/her competitor.

The role of a wholesaler is to distribute products and provide local technical support of those products. While his/her territory operates under a franchise agreement, marketing goals encourage him/her to enlist and equip qualified contractors. Key to sustainability is multiple choices for after-market services. If the original installer successfully delivers excellence, by all means, stay with the contractor for after-market care. On the other hand, if the final product is less than excellent, you want options and open systems give you options. Franchised contractors can hold you hostage.

How Does a Building Owner Assure an Open System?

We use Tridium JACE platforms, running Niagara Framework to build open systems that fully integrate control systems components, regardless protocols, to operate seamlessly and reliably.

Which Is The Better Protocol?

The goal of Rockwall Controls is to provide problem-free, low-maintenance, reliable systems that never suffer obsolescence, due to introduction of new technologies that replace current products. The key is the adoption of standards that transcend the evolution of technologies.

Autonomous processing, the quality of a control system that “pushes out” programming and functionality to the lowest possible level, contributes to the aforementioned goal. At the time of this writing, LonMark profile products lead the pack, but others are following along.

Over recent years, competing manufacturers have touted LonMark over BACnet, and vice versa. Large sums of money have been invested to promote the virtues of one protocol over the other. But, Rockwall Controls remains neutral, in this respect. Whichever answers the problem – which products operate on a peer network – guide our choices.

An emerging technology, Sedona Framework, seems to make a giant leap well beyond the two competing protocol “giants”. One new product we now use employs Sedona Framework as an operating platform as it readily ignores the protocol issue by offering on-board LonWorks, BACnet, MODBUS and IP protocols – all at the same time.

The exciting feature of Sedona is its “open source” architecture that removes all limits to product development.

Which Protocol Should I Choose?

None. That is a task best left to professionals, like the system integration experts at Rockwall Controls Company, Inc.

Got a Problem With Your Proprietary Building Automation System? Call on the experts. Call on us to turn your “manual-mation” system into an automation system.

The BEST Question – Aren’t all the above described protocols “open”?

Ah, glad you asked. In a word – no.

One major manufacturer sells its LonMark products as LON and as non-SNVT. This company maintains a proprietary lock on the system by turning off one layer of the LonMark protocol, leaving the customer at the mercy of the manufacturer.

Another manufacturer sells its top-level controllers as BACnet over Ethernet – translation: it’s a proprietary form of BACnet. An open product, an open system, allows products of other manufacturers to be attached to the BACnet bus and communicate directly. This particular manufacturer requires a “gateway” module that permits third-party BACnet over IP products to communicate.

Still other manufacturers program and commission their products with proprietary software – this alone locks up the system.

You can depend on Rockwall Controls to work with these proprietary manufacturers to break their proprietary lock on your business.

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