Fix Defined Firewall (One-way Firewall)


The Fix Defined Firewall links computers to networks with no feedback, so that the computers are able to receive only. All received network packets are passed on in one direction to the reading host. Data traffic to the safe network is not possible – neither from the reading computer nor from the firewall itself.

Manufacturer: Wiesemann & Theis / Country of Origin: Germany


  • 2x Ethernet 100BaseT
    • Autosensing/Auto-MDIX

Power supply:

  • External power
    • Screw terminals, 24V-48V DC
  • Power-over-Ethernet (PoE)
    • Phantom power using data pairs
    • Power over unused wire pairs

Standards & more

  • Conforms to standards both in office and industrial environments:
    • High noise resistance for industrial environments
    • Low noise emission for residential and business areas
  • 5 year guarantee


Feedback-free network connection

The Fix Defined Firewall is a fixed configured firewall for unidirectional data flow. Data packets arriving at the input are passed transparently to the output, with the opposite direction completely blocked. This pre-configuration cannot be changed. The Fix Defined Firewall has no configuration interface, none of its own network services, and no Ethernet address. For applications for example in telemetry or data flow analysis this ensures feedback-free connection of receiving computers to a network with high security requirements.

Due to its clearly defined scope of function the firmware for the Fix Defined Firewall needs no traditional operating system and is free of open source and third-party components.

Startup is true plug and play, and in PoE environments requires only connection of the network cables. Without PoE, the supply voltage is additionally required – that’s it.

Connections and displays:

  • Network:
    • 2x 100BaseT Autosensing/Auto-MDIX
    • RJ45
  • Galvanic isolation:
    • Network connections min. 1500 V
  • Supply voltage:
    • Power-over-Ethernet (PoE) or
    • DC 24V .. 48V (+/-10%) and
    • AC 18Veff .. 30Veff (+/-10%)
  • Supply connection:
    • Plug-in screw terminal, 5.08mm spacing
    • Labeled “L+” and “M”
  • Current consumption:
    • PoE Class 1 (0.44W – 3.84W)
    • or for external supply:
    • typ. 80mA @24V DC
    • max. 95mA @24VDC
  • Indicators:
    • 2x LEDs for network status
    • 1x LED system
    • 1x LED power

Housing and other data:

  • Housing:
    • Plastic compact housing for top-hat rail mount
    • 105x22x75mm (LxWxH)
  • Enclosure rating:
    • IP20
  • Weight:
    • approx. 120g
  • Ambient temperature:
    • Storage: -40..+85°C
    • Operating 0..+60°C (non-contiguous mounting)
  • Permissible relative humidity:
    • 5..95% RH, non-condensing
  • Scope of delivery:
    • 1x Fix Defined Firewall
    • 1x Quick Guide
Weight 0.2 kg