W&T connects
Interfaces for TCP/IP, Ethernet, RS-232, RS-485, USB, 20mA, glass and plastic fiber optic cable, http, SNMP, OPC, Modbus TCP, I/O digital, I/O analog, ISA, PCI
Data sheet:

Digital-I/O Extender Set 8*In / 8*Out Multimode ST

Reliably send contact signals over long distances

The Digital I/O Extender Set 8x8 sends up to 16 digital I/O signals over multi-mode fiber optic cable. The set consists of two Digital-I/O <> glass fiber optics and supports eight I/O channels in each direction.



  • 8 x digital output
    • FET, short-circuit protected, 8..30V / 0.5A
  • 8 x digital input
    • Polarity reversal protected
  • 1 x multi-mode fiber optic cable
    • ST connector

Management and connectivity:

  • Noise-immune transmission of 16 I/O signals over a distance of up to 3800 meters, e.g.:
    • in extremely noisy industrial environments
    • in areas subject to lightning strikes
    • between two distant buildings
    • in the mountains
    • ....
  • Safety-optimized solution
    • No need for programmable components: No firmware risk
    • Integrated monitoring of the fiber optic connection: Status output on each converter
    • configurable output response when glass-fiber cable is interrupted

Power supply:

  • External
    • 8V-30V DC using plug-in screw terminal

Standards & more

  • Conforms to standards both in office and industrial environments:
    • High noise resistance per EN 61000-6-2
    • Low noise emission per EN 55032:2015 + A1 Cl. B, EN 61000-3-2 & EN 61000-3-3
  • 5 year guarantee

Worth knowing

Although digital I/O signals are essentially insensitive to external noise due to their low bandwidth and the large voltage swing, as serial data signals for example the application conditions do still in many cases require transmission procedures which are completely resistant to local noise effects.

Glass fiber optic cables used as the transmission medium meet these requirements in ideal fashion and also offer the advantage of galvanic isolation of up to virtually any value between the connected devices. In installations which are subjected to high risk of lightning strikes, for example in outdoor locations or between distant buildings, such a solution ensures that the connected components will survive even under adverse conditions.

The W&T Digital-I/O Extender Set 8x8 is fully implemented in hardware, so that there is no principle risk of malfunction caused by hidden firmware errors or by a system crash.

The functionality of the glass fiber optic connection is cyclically monitored and the status indicated by means of an LED and a switching output. Should the connection fail, the fallback state can be individually set for each digital output.

Technical data

Connections and displays:

  • I/O connection:
    • Plug-in screw terminal
  • Digital outputs:
    • 8 x Digital Out 8V-30V, 500mA, short circuit protected,
    • configurable response to failure of the optical connection
  • Digital inputs:
    • 8 x Digital In, max. input voltage ±30V,
    • protected against reverse connection within this range,
    • Switching threshold 9V ± 1V, "On" current = 2.2mA
  • Glass fiber connection:
    • ST plug adapter
  • Supported signals:
    • 16 digital signals (eight in each direction)
  • Signal propagation time:
    • Input to output: max. 20ms
  • Fiber optic medium:
    • Multi-mode fiber 50/125μm, 62.5/125μm
  • Transmitter type:
    • LED
  • Wavelength:
    • 820nm
  • Optical budget:
    • 50/125µm: typically 9.6dB, min. 4.2dB
    • 62.5/125µm: typically 13.4dB, min. 8.0dB
  • Maximum distance:
    • 50/125µm: typically 3200m, min. 1400m @3dB/km
    • 62.5/125µm: typically 3800m, min. 2200m @3.5dB/km
  • Supply voltage:
    • 8..30V DC
  • Current consumption:
    • typ. 20mA @12V DC
  • Supply connection:
    • Plug-in screw terminal, 5.08mm spacing
    • Labeled "L+" and "M"
  • Displays:
    • 8x LED inputs
    • 8x LED outputs
    • 1x LED Link
    • 1x LED Power

Housing and other data:

  • Housing:
    • Plastic housing for top hat rail installation
    • 105 x 45 x 75mm (L x W x H)
  • Enclosure rating:
    • IP20
  • Weight:
    • approx. 400g
  • Ambient temperature:
    • Storage: -40..+70°C, Operation: 0..+70°C
  • Permissible relative humidity:
    • 5..90% relative humidity (non-condensing)
  • MTBF:
    • 326,086h @25°C per MIL-HDBK-217
  • Life expectancy:
    • > 25 years at 25°C ambient temperature
  • Scope of delivery:
    • 2 Converters Digital-I/O <> Multi-Mode Glass Fiber
    • If needed please order power supplies as separate accessories


*Net unit price for
commercial users
  • Power supplies

    • Plug-in power supply, 24V / 500mA DC with Euro plug
    • 11021
    • 21.00€
    • Plug-in Power Supply, 24V / 750mA DC with Euro, US and UK plug
    • 11026
    • 38.00€
    • Power supply for DIN rail, 24V / 630mA DC
      (merchandise, 2-year manufacturer’s guarantee)
    • 11080
    • 33.00€
  • FO-Accessories

    • Patch cable ST/ST, 1 meter, 50/125um
    • 81901
    • 16.00€
    • Patch cable ST/ST, 2 meters, 50/125um
    • 81902
    • 21.00€
    • Patch cable ST/ST, 5 meters, 50/125um
    • 81905
    • 26.00€
    • Patch cable ST/ST, 10 meters, 50/125um
    • 81910
    • 37.00€
    • Patch cable ST/ST, 15 meters, 50/125um
    • 81915
    • 42.00€
  • Mechanical Accessories

    • Mounting bracket for wall mounting
    • 58812
    • 11.20€
    • 19" DIN rail
    • 58813
    • 21.00€

* Our offering is intended only for commercial users. We will be happy to refer private end customers to trading partners through whom our products can be purchased.