Convert Serial (RS-232/422/485) to Fiber

RS-232, RS-422, and RS-485 are the most popular serial interfaces in the industrial application. Each interface provides unique benefits for device communication.

Serial over Fiber Overview

Due to the easiness of setup and low cost, serial devices are used around the world of industrial systems. If greater distances are required, RS-485 increases the distance to 400 feet (or 1200 meters). However, the longer the copper cable, the more data corruption due to the electromagnetic (EMI) and radio frequency (RFI) interference. The fiber connection provides the benefits of noisy immunity and distance. Serial over Fiber is the best solution to overcome these problems, and the data/singles can be transmitted up to 40 km distance.

How does it work?

  • Pair Connection Mode

The Pair Connection simply extends the point-to-point transmission distance of the serial connection. Two serial-to-fiber converters can be connected over a fiber cable between a computer and a serial device. These two locations can be up to 12 miles (20 km) apart. Beware the flow control signals for RS-232 cannot be transmitted over fiber. The DTR/DSR and RTS/CTS needs to be shortened for RS-232 application.

  • Ring Connection Mode

If multiple serial devices need to be connected, the Ring Connection mode provides a cost-effective solution. The serial-to-fiber converters can inter-connect to the neighboring converters and form a closed fiber-to-serial ring. Data packets are transmitted by one converter to the other and so on until the signal returns to the converter that sent the original signal. When using the Ring Connection mode, the total length of the fiber connection is up to 62 miles (100 km). The only drawback is the failure of one fiber connection will cause the entire system to fail.


Here are the products which have the features explained on this page.

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