ION 10 Gigabit Ethernet Media Converter Module
10GBase-T Copper to Fiber

The C4120 is a media converter module that provides an interface between 10GBase-T ports and 10GBase-X ports via an open SFP+ port, allowing users to convert their 10Gig Ethernet ports to the preferred type of cabling used in their networks. The open SFP+ port supports a wide variety of Lantronix 10GE SFP+ fiber modules. Operating at Layer 1, the physical layer, data is passed through the converter at line speed, making the C4120 ideal for applications where low latency is essential. The ION C4120 is a manageable device when installed in a managed ION chassis.

NDAA Compliant

C4120-1048 Overview


  • Transparent Link Pass Through
  • Auto-Negotiation
  • Auto-MDI/MDIX
  • Automatic Link Restoration
  • Loopback on Fiber and Copper
  • DMI
  • For use in the ION 19-Slot or 6-Slot Chassis only
  • Manageable when installed in a managed ION Chassis
  • Remote Firmware Upgrade Fiber Port supported standards
    • 10GBase-SR
    • 10GBase-LRM
    • 10GBase-LR
    • 10GBase-ER
    • 10GBase-ZR
  • The open SFP+ port also supports:
    • Direct attached 10G copper cable assemblies
    • Both Class-I and Class-II fiber
    • SFP+ modules
    • SFP modules supporting WDM technology
  • Support 100m on Cat6a or higher UTP
  • Per Energy Efficient Ethernet standards, IEEE 802.3az, UTP cable length is detected and power is adjusted according, to reduce power consumption on shorter UTP cable installs

C4120-1048 Tech Specs


  • IEEE 802.3
  • IEEE 802.3an
  • IEEE 802.3ae
  • IEEE 802.3az

Data Rate

  • 10 Gbps

Dip Switch

  • SW1: Copper Loopback
  • SW2: Fiber Loopback
  • SW3: not used
  • SW4: Transparent Link Pass Through

Status LEDs

  • PWR (Power): On = power is on
  • L/A SFP+ (Fiber port link and activity statue): On = Link OK
  • Flashing = Link and Activity OK
  • Copper Link (Copper Link Status): On = Link OK
  • Copper Act (Copper Link Activity): On = Activity OK


  • Width: 0.86” [21.85 mm]
  • Depth: 6.5” [165 mm]
  • Height: 3.4” [86.36 mm]

Power Consumption

  • 10.5 Watts (See product manual for chassis power guidelines)


  • Environment specs are dependent on the chassis chosen
  • Operating: 0°C to 50°C
  • Humidity: 5% to 95% (non-condensing)
  • Altitude: 0 – 10,000 ft.


  • 1 lb. [0.45 kg]


  • Greater than 250,000 hours (MIL-HDBK-217F)
  • Greater than 687,000 hours (Bellcore)


  • FCC Class A, EN55022 Class A, EN55024, CE Mark


  • Lifetime

C4120-1048 Downloads

Additional Product Information

Note: Some Documentation may have Transition Networks named or pictured. Transition Networks was acquired by Lantronix in August 2021. Learn more about the acquisition here.

Firmware Downloads

Keep your products up to date by downloading the latest firmware. You must log in or create a MyLantronix account to download firmware. 

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