Sunday, January 3, 2010


What is a Fiber Optic Converter and When Do You Need One?

When most people think of serial data converters, they think of RS232, RS422, RS485, TTL, USB and other serial data communication protocols, or perhaps even connections to Ethernet. So where do Fiber Optic converters and adapters come into play?

Fiber optic connections are used in situations where the serial communication protocols' speed and distance limitations interfere with a project. What are some of these limitations? It can be voltage swings, signal interference, electrical surges, or the need for absolute immunity to electromagnetic and radio frequency disturbances. Keep in mind that serial data communication protocols were mostly conceived decades ago when communication speeds were only a very small fraction of what they are today. As a result, while serial communication technologies and standards have proven remarkably adaptable, they were simply never meant to handle some of the complex and super-fast applications they are still being used for today.

In many of those applications, fiber optics is the answer. They use light instead of electrical current to carry signals. These connections provide much higher speed, high bandwidth, and they are inherently immune to radio and electromagnetic interference. This makes fiber optics perfect for serial communication applications that require very high speed or must transfer signals over much longer distances than RS-232, RS-485 or RS-422 can handle, or both.

But aren't these systems too complex for most projects, and aren't copper and optical communication systems incompatible? The answer is "no" to both statements.

As far as technology goes, including fiber optics to a copper-based data communication system requires little more than a transmitter, a receiver, and the fiber optic cable itself. There are some decisions to be made, such as building a single-mode system that uses a single strand of fiber for high-speed long distance communication or a multi-mode system based on less expensive multi-strand fibers. In terms of distance, multi-mode systems can generally extend a serial connection up to about 1.2 miles whereas a single mode system can be used for distances over 12 miles.

As far as converters go, they have come a long way since they were introduced a couple of decades ago. Today's converters are usually auto-sensing, self-adjusting and completely hassle-free. There are no manual settings or switches to figure out, and the converters are hot-pluggable. Fiber optic converters usually come with an external AC/DC power adapter and, depending on the system, may require either SC ("Subscriber Connector") or ST ("Straight Tip") connectors. There are numerous other optical connector types, so make sure you order the right one.

Note that this is not simply a way to "hot-rodding" a slow serial communication system. While optical fibers theoretically can handle almost unlimited speed, the ultimate speed is still determined by whatever RS232/422/485 serial data rate is possible in a system. For serial data communication systems, the maximum data rate is usually around 460kbps. When used in an Ethernet-based system, of course, the converter can easily handle 10BaseT or 100BaseT speeds, and gigabit-capable converters are available as well.

What this all means is that distance is not the limit it once was for serial data communication. Fiber optics can greatly extend serial communication reach, and the required adapters and converters are inexpensive, reliable, and easily available.

Chris Robertson is an author of Majon International, one of the worlds MOST popular internet marketing companies on the web.
Learn more about RS422 Converters.

Article Source: Robertson

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