You may have noticed that certain network communication protocols are available from only a very limited number of manufacturers — sometimes just one. When that's the case, they're almost certainly closed communication protocols.

These protocols are proprietary, meaning users need a license to design their own devices or interfaces for them. The specifications of a closed protocol are restricted, typically available only to licensees rather than the general public. Devices that use these protocols are black boxes: very little is publicly known about how they work internally.

Open communication protocols, by contrast, are non-proprietary and non-restrictive. Developers freely share specifications covering data formats and electrical design.

Device or interface designers who work with open protocols can build and commercialize products without paying any licensing fees. For end users, this translates to a wider range of compatible devices from multiple manufacturers — generally at lower prices, driven by healthy market competition.

Why Use Closed Communication Protocols?

One common reason to choose a closed protocol is configuration simplicity: the manufacturer's software often streamlines setup in ways that save real development time and cost. Another factor is trust — confidence in the technical support provided by the equipment or software vendor behind the protocol.

That said, closed protocols always carry a significant drawback: limited expansion options down the road. Users are locked into whatever equipment the manufacturer offers. If a needed piece of functionality isn't in the vendor's catalog, the only option is to bring in equipment from a different manufacturer using a different protocol — and that means managing multiple communication networks with all the complexity that entails.

Limited competition among closed-protocol manufacturers, compounded by licensing costs, also gives vendors room to raise prices over time.

Why Use Open Communication Protocols?

Open communication protocols offer several concrete advantages:

• Cost: Competition among manufacturers of open-protocol products drives prices down. Shared contributions to protocol development distribute costs more equitably across designers and developers.
• Equipment availability: Open protocols give users the freedom to choose from a broad range of products across multiple manufacturers, which dramatically increases the chance of finding a device with exactly the functionality required.
• Information availability: With open protocols, users can assess how well any given manufacturer actually meets the protocol's requirements. They also gain access to open-source software tools for analyzing device behavior — Wireshark being a well-known example.

Ultimately, the choice of protocol should be driven by the user's short- and medium-term needs. The comfort that comes from trusting a particular vendor and their support organization comes at a cost — one that can rise further if the system needs to expand.

Open protocols, on the other hand, offer the equipment availability and technical transparency to match real-world requirements, including budget constraints. On the surface, the answer seems obvious — but the final call always belongs to the user.