• Free Topology Twisted Pair Transceivers

• Junction Box and Wiring Guidelines
• Echelon Transceivers

What's Free Topology Technology?

A conventional control system using bus topology wiring (such as RS-485) consists of a network of sensors and control outputs that are interconnected using a shielded twisted wire pair. In accordance with RS-485 guidelines, all of the devices must be wired in a bus topology to limit electrical reflections and ensure reliable communications. There's a high cost associated with installing and maintaining the cable plant that links together the many elements of an RS-485-based control system. Bus topology wiring is more time-consuming and expensive to install because installers can't branch or star the wiring where convenient: All devices must be connected directly to the main bus.

The best way to reduce installation and maintenance costs and simplify system modifications is a free topology communication system. Our free topology transceiver technology offers such a solution, and provides an elegant, inexpensive way to connect the different elements of a distributed control system.

A free topology architecture lets you wire the control devices with virtually no topology restrictions. Power is supplied by a local +5VDC power supply located at each device.

Unlike bus wiring designs, the free topology FT 3120 and FT 3150 Smart Transceivers support star, loop, and/or bus wiring. This has many advantages:

• Installers can select the wiring method that best suits the installation, reducing planning time and allowing last-minute changes on site.
• If installers have been trained to use one wiring style for all installations, they can do so—no need for retraining.
• Retrofit installations with existing wiring plants can be accommodated with minimal, if any, rewiring. This lets you adapt FT 3120 and FT 3150 Smart Transceiver technology to both old and new projects.
• Free topology lets you expand FT 3120 and FT 3150 Smart Transceiver systems in the future by simply tapping into the existing wiring where it's most convenient to do so. For installers, this reduces the time and expense of system expansion; for customers, it reduces the life-cycle cost of the free topology network.

Typical wiring topologies supported by the FT 3120 and FT 3150 Smart Transceivers System (* The actual termination circuit will vary by application.)