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Features / Benefits

  • Interface - ITU V.35, V.11 compliant with MR-34 Female Connectors
  • Data Rates - 1.2k to 3.072M - 32 Selectable Rates
  • Serial Data Interface cards are Interchangeable and may be mixed such as V.35 to RS-530
  • Controls for RTS/CTS delay, DSR, DTR on a per port basis
  • Timing - Internal
  • Status LEDs for each Serial Port and Signal
  • 110/220VAC switch selectable or DC Power for -48VDC
  • UL, CSA and CE Approved, RoHS
  • Sturdy Metal Aluminum Enclosure


The Digital Mixing Module X.21 (DMM-X21) provides the network manager with a cost effective means of expanding existing, leased line polled networks without adding computer ports or communications links. With the DMM-X21, up to 4 DTE or DCE devices can share the same port and communications link using the contention and control protocols normally resident in the host hardware and software.

Once installed, system and network efficiency are increased through higher host processor utilization coupled with the significant decrease in idle time between host / terminal traffic sessions.

Ideal for synchronous network environments, the DMM-X21 is protocol transparent at data rates up to 1.024Mbps. Data arriving at the Master Port is continually broadcast to all Subchannels. The attached terminal device that raises the Control (C) or Indicate (I) signal is automatically given control of the DMM-X21 until data transmission is complete. Clocking is accomplished from the attached Digital Modem.

The DMM-X21 incorporates optional Anti-Streaming circuitry. If enabled, Anti-Streaming will automatically remove a defective terminal from service if the Control (C) or Indicate (I) signal is present longer than the user predefined selection period.

Elastic Tail Circuit Buffers compensate for systems having different clock sources. Large 512 bit buffers enable the DMM-X21 as an ideal choice for VSAT or land line applications.

The DMM-X21 is equipped with an internal 110/220VAC switch selectable linear power supply and has a three year warranty.The UDC-ME V.35 modem eliminator allows two DTE devices (such as routers) to communicate within proximity of each other. The UDC-ME transmits data bidirectionally at clock rates of 1.2k up to 3.072Mbps between DTE devices. All clocking and signal crossover are provided within the UDC-ME. The unit is equipped with two interface slots that allow a host of serial interface cards to be utilized. The serial interface cards available are RS-232, RS-422/449, RS-530, X.21, V.35 and HSSI. The Serial Interface cards are interchangeable and may be mixed such as RS-232 to V.35 thus eliminating the need for an interface converter or changing expensive serial cards on a DTE device such as a router.

The UDC-ME V.35 modem eliminator is also an excellent choice for testing router-to-router connections via the serial ports. The unit is an excellent choice for interconnecting your LAN or legacy mainframe equipment.

Installation is fast and simple by setting the internal switches for Clocking, Carrier Operation and RTS to CTS delay. The UDC-ME has status LEDs for each attached DTE device which allows the user to visually confirm the presence of clock and control signals.

The UDC-ME utilizes state of the art digital CMOS technology to provide a feature filled product at a very affordable price. Our Field Programmable Gate Array (FPGA) design has allowed us to offer this product with a wide selection of clock rates. This design approach has also reduced the amount of clock jitter for high speed transmissions.

The UDC-ME is housed in a sturdy metal enclosure and operates on 110/220VAC or optional -48V DC power. Typical MTBF figures are in excess of 150,000 hours of operation.

The UDC-ME has a three year warranty and a 24 hour turnaround on warranty repairs.



Application Interconnection of two DTE’s (such as Routers) located within proximity of each other
Capacity Two (2) DTEs
Interface V.35 or RS-232, RS-422/449, RS-530, X.21 and HSSI
Data Format Data Transparent at all Data Rates
Inversion Option Data Inversion or Clock Inversion
Selectable Clock Rates 1.2k, 2.4k, 4.8k, 7.2k, 9.6k, 14.4k, 16k, 19.2k, 28.8k, 32k, 38.4k, 48k, 56k, 57.6k, 64k, 72k, 96k, 128k, 192k, 256k, 384k, 512k, 768k, 1.024M, 1.280M, 1.472M, 1.536M, 1.544M, 1.920M, 1.984M, 2.048M, 3.072M
Surge Protection Main power supply
Optional Accessories 1) Spare Data Center Fuses
A) 160ma Fuse, Qty (2) Part # 714000
B) 80ma Fuse, Qty (2) Part # 714001
Power Source AC Mains: 100-120 to 200-220VAC @10%, 50/60Hz, 0.16/0.08A, external 110/220 volt select switch, IEC
Power Inlet, (2) 5mm Fuses
DC Mains: DC Voltage, Input Range of -36 to -72vdc
Current Draw at 48vdc: 75ma @ 3.6watts
Environmental Operating Temperature....32º to 122º F (0º to 50º C)
Relative Humidity.............5 to 95%
Altitude............................0 to 10,000 feet
Dimensions Height ....... 1.75 inches (4.44 cm)
Width ........ 9.00 inches (20.86 cm)
Length ...... 9.00 inches (20.86 cm)
Weight 2 pounds (0.914Kg
Warranty Three Years, Return To Factory
Regulatory Approvals Tested According to UL 60950-1:2003, CAN/CSA-C22.2 No. 60950-1:2003CE Safety EN60950 and CE EMC EN300-386-2
Ordering Information
PT # 189000 – (Small Chassis) Model: UDC-ME Base Standalone Unit
Description: UDC Modem Eliminator, Standalone, Rates 1.2k to 3.072Mbps
PT # 200000 – (1U Rackmount) Model: UDC-ME 1U Rackmount Unit
Description: UDC Modem Eliminator, 1U Rackmount, Rates 1.2k to 3.072Mbps
PT # 246000 – (1U Rackmount) Model: UDC-ME High Speed
Description: UDC Modem Eliminator, High Speed, 1U Rackmount, Rates 3.2k to 8.192Mbps

Serial Interface Cards, Two Cards Required Per UDC-ME, pick any two cards, may be the same card twice or any combination.

129014 RS-232 DCE I/M, DB-25 Female
129010 V.35 DCE I/M, MR-34 Female
129011 RS-530 DCE I/M, DB-25 Female
129012 RS-422/449 DCE I/M, DB-37 Female
129013 X.21 DCE I/M, DB-15 Female
151028 HSSI DCE I/M, 50 Pin Female
Included with each unit: 1) Operations Manual
2) U.S.A. Grounded Power Cord, Part # 713015
3) Optional Power Cords
A) United Kingdom, Part # 713016
B) Continental Europe, Part # 713017
C) Other: Specify Country on Purchase Order