FM4500: E1 to E1 and 4x X.21 / V.35 Multiplexer

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The Metrodata FM4500 DSU is used as a drop/insert multiplexer to merge voice and data applications onto a single E1 2.048 Mbps link.

Front: FM4500FM4500 rear

Fractional E1 (Nx64kbps) G.703/G.704 to E1 + Multiple X.21/V.35 Multiplexer

FM4500 as an E1 TDM multiplexer

The FM4500 used as an E1 drop/insert multiplexer to converge voice and data applications

  • Share a Single E1 Leased Line for Both Voice and Data Services
  • High Spec E1 G.703/G.704 2.048 Mbps TDM Multiplexing
  • One E1 Drop port and Four Nx64kbps Data ports (either all X.21 or all V.35)
  • External Alarm relay port
  • Local management port for configuration and diagnostics
  • Remote configuration and testing of units across the network
  • Comprehensive performance monitoring of both device and line
  • Built to European standards
  • Optional remote management using SNMP and Telnet
  • Optional -48 volt DC supply

Router Applications

converging multiple voice and data applications across an E1 2Mbps G.703/G.704 leased line

FM4500 converging multiple voice and data applications across an E1 2Mbps G.703/G.704 leased line

This application shows a pair of FM4500 units connecting together 2 sites with multiple independent applications via an E1 G.703 2.048Mbps leased line, such as a BT Megastream-2 service. X.21 serial ports are often the most cost effective WAN port available on routers and other equipment such as video conferencing equipment, whilst PBXs have Fractional E1 G.704 interfaces. The FM4500 multiplexes all of these different voice and data information streams together onto a single E1 circuit, and then demultiplexes them back out again at the remote site.

FM4500 being used to converge multiple sub rate Nx64kbps services onto a single E1 2Mbps G.703 leased line


This application shows an FM4500 unit connecting four Nx64kbps sub rate services over a single E1 2Mbps G.703/G.704 leased line. In this way several sites in close proximity can be connected together via cheaper leased lines and share the cost of a single longer distance leased line thereby enabling considerable savings. Multiple FM4500 units can be cascaded in this application through connection via the E1 drop port.

LM1100 SNMP Enabler used with Management Data link to manage a pair of FM4500 units

FM4500 remote management using LM1100 and datalink

This application show a remote network management centre controlling the head office FM4500 via an LM1100 SNMP Enabler card allowing comprehensive management access including the full range of configuration changes, diagnostics and status analysis using either SNMP or Telnet, including SNMP traps. In this application a remote management data link has also been enabled to the remote FM4500 unit, allowing remote SNMP and Telnet access into this unit.

The FM4500 offers conversion between multiple X.21 or V.35 serial interfaces (either all X.21 ports or all V.35 ports) and an E1 line interface with BNC or RJ45 connector options. An E1 drop port is also supported for connection to a PBX or E1 router, or alternatively cascading onto another FM4500 unit (either both E1 ports have BNC connectors or both have RJ45 connectors).

Fractional operation allows a number of 64kbps timeslots to be active, up to a maximum of 31 timeslots for a single E1 line. If timeslot 16 is bypassed, then a maximum of 30 timeslots (channels) can be accommodated between the 5 user ports.

The FM4500 has several LEDs for displaying current status, plus comprehensive configuration and diagnostics via a menu driven user interface.

It is possible to connect the FM4500 to EIA-530 or RS-449 equipment using conversion cables.

Using a dedicated management timeslot pairs of FM4500 units can communicate with each other, allowing configuration and status checking of the remote unit.

The optional Metrodata LM1100 SNMP enabler permits remote management via either Telnet or SNMP.

E1 Line Interface
Port G.703, 75 ohm unbalanced or 120 ohm balanced
Interface BNC (75ohm) / RJ45 (120ohm) (both interfaces must be the same)
Framing G.704 (with or without CRC4)
Line Coding HDB3
Bit rate 2.048Mbps +/- 50ppm
Barrier Fully compliant as per EN41003
Cable Lengths BNC: RG59 = 600m, UR202 = 750m
RJ45: Belden 8132 = 175m, Belden 9841 = 300m

DTE Interface
Port X.21 or V.35 (all four interfaces must be the same)
Interface X.21: ISO4903 15 way female D-type
V.35: ISO2593 34 way M-rack
Bite Rate Nx64kbps (N = 1 to 31)

Configuration & Management
Type Menu Driven
Access System console, Telnet, SNMP
Interface V.24, Ethernet 10 BaseT via RJ45
Security Access by 2-level password
System Non volatile configuration
Line E1 Timing Internal, Loop, Through, Terminal Timing (CCITT cct 113), DTE mode (CCITT cct 113)

Status LEDs & Diagnostic Functions
Loop backs Local loop, Remote loop
Statistics Per G.821, 15 min, 24 hour totals
Major Alarm LEDs LOS, LOF, SQ (per E1 port)
Minor Alarm LEDs AIS, RAI (per E1 port)
Data LEDs DTE Tx Data, DTE Rx Data, DTE Fault (per X.21/V.35 port)
Test LED Test in progress LED, test configured via diagnostics menu

Power Supply
AC Mains 100 - 250 VAC, 50 - 400Hz, 50mA IEC connector
-48VDC -36 to -72 VDC, 200 - 100mA, Buccaneer connector

Type 1.5U 19 inch Rack mount
Dimensions 435 x 213 x 65mm (W x D x H)

Temp 0 - 50 deg C
Humidity 95% RH, non-condensing
Pressure 86 - 106 KPA

Compliance & Approvals
Performance G.703, G.704, G.706, G.823
BNC Version OTR.001 2DS, BABT#NS/4043/I/P/604060
RJ45 Version CTR12, CTR13, BABT#606272
Safety EN41003, EN60950
EMC EN55022, EN50082
Statistics G.821, AT&T54016: 15 min, 24 hour totals
Management RFC1213 (MIB2), RFC1495 (Telnet), RFC1157 (SNMP), RFC1406 (DS1/E1)
MetroDTE MIB (X.21/V.35), RFC1215 (Traps)
Part Number
Product 100-250 AC Mains -48 DC Power
E1 BNC to X.21 80-05-009 80-21-009
E1 BNC to V.35 80-05-010 80-21-010
E1 RJ45 to X.21 80-05-011 80-21-011
E1 RJ45 to V.35 80-05-012 80-21-012
LM1100 SNMP Enabler 14-02-139 14-02-139

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