X22 - Bi-directional TTL to Fiber-optic Converter

The X22 is a bidirectional TTL to the fiber-optic converter in a small form factor. It lets the user convert to and from fiber-optic signals to and from digital voltage signals. The unit is independently powered from an isolated power supply, allowing for high voltage isolation between TTL input and outputs when two X22s are used as a pair.

The polarity of conversion is configurable with two physical switches one for each direction. TTL inputs can be high impedance or 50 ohm, settable with an internal jumper specified when you order. The fiber optic connectors can be either ST type or Versatile Link style specified when you order. The X22 is built with robust components for reliable performance under many operating conditions.

The X22 can be used to convert UART communication signals, like RS232, to and from fiber optics using standard baud rates.

For unidirectional TTL to fiber applications that can drive 30mA the TF-1 may be a simpler choice.

If you wish to "fan-out" the signal to multiple fiber outputs, see the X14 device.


  • Converts fiber-optic signals to TTL, and TTL to fiber-optic
  • Works at standard RS232 baud rates
  • Switch selectable polarity in either direction
  • Choice of ST bayonet or Versatile Link fiber optic connectors
  • Visible light (650 nm red)
  • Compatible with 1mm plastic or 200 um HCS multimode fiber
  • TTL input can be high impedance (> 1 Mohm) or 50 ohm, internal jumper selectable
  • Optional DIN rail mounting
  • Compact stainless-steel chassis


  • Trigger and logic-level signal delivery in large distributed systems
  • High voltage digital I/O isolation
  • General UART or RS232 fiber optic conversion or isolation
  • General-purpose logic signal conversion

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