Versitron Fiber Optic Modem Manuals Resource



1000 Base T-SX/LX

Media Converter






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83 Albe Drive / Suite C

Newark, DE 19702


All VERSITRON products purchased after January 2001 carry a limited lifetime warranty against defects in material and workmanship. Purchases made prior to January 2001 are warranted for a period of one year from date of delivery. VERSITRON reserves the right to repair or, at our option, replace parts which during normal usage prove to be defective during the warranty period provide that:

1. You call VERSITRON at (302) 894-0699 or (800) 537-2296 and obtain a (RMA) Return Authorization Number. Please reference your RMA number on the outside of the box in which the item is returned.

2. Shipping charges are pre-paid.

No other warranty is expressed or implied and we are not liable for consequential damages. For repairs outside of the warranty period, the same procedure must be followed.




General Description

The M725X Gigabit Ethernet media converter series provides a conversion allowing Gigabit integration of fiber optic and copper (twisted-pair) segments. It is used to extend the connection distance between two copper Gigabit Ethernet devices via fiber optic cable transparently with no performance degradation.


Key Features

    • Compliance with 802.3ab 1000BaseT and 802.3z 1000BaseSX/LX standards
    • Auto-negotiation function built in twisted-pair port that allows operation at optimal configuration connecting to an auto-negotiation capable device
    • Auto MDI/MDI-X crossover configuration and receiving polarity error correction on a twisted-pair interface
    • Supports low cost multimode fiber and single mode fiber cable when long reach connection is needed.
    • Extends network span up to 40Km over duplex single mode fiber cable
    • Switch selectable enable or disable auto-negotiation function of the fiber port when connecting to a non-auto legacy 1000BaseSX/LX device
    • Full LED indicators to monitor port and connection status



This guide covers the following converter models:

M7254 UTP to 220m (or 500m) SC multimode fiber

M7255 UTP to 10Km SC single mode fiber

M7255-4 UTP to 40Km SC single mode fiber


The outline of the converter is:





1.1 Specifications

Twisted Pair Interface

    • Compliance 802.3ab 1000BaseT
    • Connector Shielded RJ-25 jack
    • Pin assignments Auto-crossover for MDI & MDI-X
    • Data speed 1000Mbps
    • Duplex mode Auto-negotiation for half/full duplex
    • Cable type 4-pair Category 5 UTP
    • Cable length 328ft (100m)

    Fiber Optic Interface

      • Compliance 802.3z 1000BaseSX/LX
      • Connector Duplex SC
      • Data speed 1000Mbps
      • Duplex Mode Forced full-duplex or auto-negotiation
      • Auto SW Auto-negotiation Enable/Disable switch
      • Cable types Multimode (MM) – 50 or 62.5/125 µm

      General Information

          • Frame Types 802.3 Std. 64Bytes ~ 1518Bytes frames VLAN tagged frames (plus 4 bytes tag)
          • Input power +5VDC (+/- 10%) 1.5A min.
          • Consumption 4 watts max. (0.8A max. A +5V)
          • Dimension H25mm x W96mm x D101mm
          • Housing Enclosed metal with no fan
          • Op. Temp. -10 ° C ~ 40 ° C (cold start 0 ° C)
          • Stor. Temp. -20 ° C ~ 70 ° C
          • Rel. Humidity 0% ~ 70%




      SECTION 2

      General Description

      2.1 Media Converters


      2.1.1 Functions of 1000BaseT Port (UTP)

        • Auto-negotiation support for connecting to auto-negotiation devices
        • Supports both half-duplex and full duplex operations
        • Auto MDI/MDI-X crossover configuration and receiving polarity correction for UTP connection

        Pin Assignments

      Pin MDI MDI-X
      1 BI_DA+ BI_DB+
      2 BI_DA- BI_DB-
      3 BI_DB+ BI_DA+
      4 BI_DC- BI_DD-
      5 BI_DC+ BI_DD+
      6 BI_DB- BI_DA-
      7 BI_DD+ BI+DC+
      8 BI_DD- BI-DC-


      2.1.1 Functions of 100BaseX Port (Fiber Interface)

      • Full data rate of 1000Mbps for full duplex operation
      • Auto SW on rear panel to enable or disable auto negotiation function as follows:

      NON-AUTO Disable auto negotiation function (forced full duplex mode)

      AUTO Enable auto negotiation function

      Note: For connecting to a 1000BaseX device, which did not provide auto negotiation capability, setting SW to NON-AUTO may prevent unexpected link failure occurrence. In most cases, the AUTO setting will work. With two of these converters at both ends of the fiber connection, set the switch to NON-AUTO (forced full duplex mode) to achieve the best performance.


      The following table lists the fiber connectors, fiber cables and the maximum length supported by each converter model:

      Model Fiber Wavelength Output Power Input Sensitivity
      M7254 SX 850nm -9.5 ~ -4dBm -12.5dBm max.
      M7255 LX 1310nm -9.5 ~ -3dBm -14.4dBm max
      M7255-4 LX 1310nm  


      Model Fiber Used Cable Length
      M7254 MM 62.5/125µm 220 meters
        MM 50/125µm 500 meters
      M7255 SM 9/125µm 10 km
      M7255-4 SM 9/125µm 40 km

      2.2 LED Indicators






      PWR Power status ON Power on
          OFF Power off
      TP-LINK UTP link status ON TP link up
          OFF TP link down
      TP FDX UTP duplex status ON TP Full duplex
          OFF TP Half duplex

      Collisions on half-duplex

      TP-RX UTP Rx status ON TP Reciever in operation
        OFF TP no receiving operation
      TP-TX UTP Tx status ON TP Transmitter in operation
          OFF TP no transmission
      FBR-LNK Fiber Link Status On Fiber Link up
          OFF Fiber Link down


      2.3 Applying Power

      The DC input of the converter is:

      DC Input Jack  
      DC input rated voltage +5VDC
      DC input voltage range +4.75 ~ 5.25VDC
      DC power consumption max. 0.8A @+5V (4 Watts)
      DC input Jack


      Before you begin the installation, check the AC voltage of your area. The AC power adapter, which is used to supply the DC power for the unit, should have the AC voltage matching the commercial power voltage in your area.

      The specifications of the AC power adapter are:

      AC input power AC power voltage of your area
      DC output power +5V minimal 1.5A

    Steps to apply power are:

    1. Connect the power adapter DC plug to the DC input jack located on the back of the converter before connecting to the AC outlet

    2. Connect the power adapter to the AC outlet

    3. Check power LED indication


    2.4 Making Connection

    The figure below shows the configuration used when connecting to an auto-negotiation device and a non-auto-negotiation device.

    For proper communications, the UTP connections on both ends must be in the same configuration, either 1000M full duplex or 1000M half-duplex. Set the Auto SW to NON-AUTO mode to use forced full duplex mode for the fiber connection.



    The information contained in this document is subject to change without prior notice.

    Copyright .All Rights Reserved

    TRADEMARKS Ethernet is a registered trademark of Xerox Corp.

    FCC WARNING This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with this user's guide, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.

    CE NOTICE Marking by the symbol indicates compliance of this equipment to the EMC directive of the European Community. Such marking is indicative that this equipment meets or exceeds the following technical standards:

    EMC Class A

    EN50081-1/1992: EN55022, EN61000-3-2, EN61000-3-3

    EN50082-1/1998: EN61000-4-2, EN61000-4-3, EN61000-4-4,

    EN61000-4-5, EN61000-4-6, EN61000-4-8, EN61000-4-11