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Standalone Chassis or Dual 1U Rackmount Chassis

Features / Benefits

  • Interface - EIA RS-232, DB-25 Female Connectors
  • Data Rates – Synch or Async to 64Kbps
  • Transparent to Data
  • External Clocking
  • Handshaking – RTS / CTS or Switch on Data
  • Anti-Streaming – Automatic or Manual for unattended Circuit Restoral
  • Receive Data Broadcast to all Sub-channel Ports
  • Individual Sub-channel Enable / Disable Switches
  • Visual Indication of Sub-Channel Activity
  • 110/220VAC Switch Selectable
  • Safety: meets new 62368-1
  • Standalone Chassis or 1U Rackmount Options
  • Sturdy Aluminum Enclosure
  • +/- 15Kv ESD Protection for RS-232 Interface


The RS232 Data Sharer or Modem Sharing Device 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 MSD-2, up to two terminals 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 either synchronous or asynchronous network environments, the MSD-2 is protocol transparent at data rates up to 64Kbps. Data arriving at the Master Port is continually broadcast to all Subchannels. The attached terminal device that raises the RTS control signal is automatically given control of the MSD until data transmission is complete. Clocking is accomplished from the attached Modem.

The MSD-2 incorporates optional Anti-Streaming circuitry. If enabled, Anti-Streaming will automatically remove a defective terminal from service if the Data / Control criteria is present for the user predefined selection period.

Housed in a sturdy metal enclosure and equipped with an internal 110/220VAC switch selectable linear power supply, the MSD-2 will provide more than 100,000 hours of reliable service.

The MSD-2 has a 3-year warranty and a 24-hour turnaround on warranty repairs.

MSD-2 Diagram



Multiple sync/async terminal or DTE devices operating in a polled environment, to share one Modem.

Capacity Standalone: One Master Port Input Port and 2-Ports for attached RS-232 Sync/Async devices 1U Rackmount: Houses two MSD-2 Units per 1U Chassis, each with its own internal linear power supply and each with IEC Power Inlet and each with its own 110/220VAC Power Swi

Three EIA RS-232, CCITT V.24 using DB-25 female connectors


Data Rates Up to 64Kbps
Data Format

Data transparent at all data rates


External; from attached Modem


OR-MODE (Switch on Data)

Anti-Streaming Automatic…Selectable time out intervals
Disable……Selectable via dip switch
Terminal Service Modes Rotational sequence for equal access
Priority Mode Optional via Dip Switch
Front Panel

Indicators: Power, CTS, DCD, RXD, TXD
Channel Active
Switches: Enable/Disable of each Sub-channel

Power Source - Power Draw

100-120 to 200-220VAC @10%, 50/60Hz, 0.16/0.08A, external 110/220 volt select switch, IEC Power Inlet, (2) 5mm Fuses

POWER DRAW: @120VAC 60Hz, 0.02 AMP, 1.9 Watts, 3.3VA

Environmental Operating Temperature: 50º to 160º F (10º to 60º C)
Operational Alt.: 0 to 10,0008 Feet above sea level
Operational Relative Humidity: 10% to 80%
Non-Operational Temperature: -30 degC to 70 degC
Non-Operational Alt.: 0 to 50,000 feet above sea level
Dimensions 1U Rackmount Tray

MSD-2_Dual-1U or MSD-2_Single-1U
Height ....... 1.75 inches (4.445 CM)
Width ........ 17.00 inches (43.180 CM)
Length ....... 9.00 inches (22.860 CM)

Dimensions Standalone Chassis

Height ....... 2.53 inches (6.426 CM)
Width ........ 8.10 inches (20.574 CM)
Length ....... 8.78 inches (22.301 CM)


MSD-2 Standalone Chassis: 3 Pounds (1.36Kg)
MSD-2_Dual 1U Rackmount Chassis: 7 Pounds (3.175Kg)
MSD-2_Single 1U Rackmount Chassis: 3.5 Pounds (1.587Kg)

Warranty Three Years, Return to Factory
MTBF 601,328 Hours
Benign Ground, Controlled, Telcordia Issue 1
Approvals EMI Approvals
FCC 47CFR, Part 15, Subpart B for conducted emissions from a Class A
FCC 47CFR, Part 15, Subpart B for radiated emissions from a Class A
Safety Approvals Meets UL 62368-1
Ordering Information 1U Rackmount Chassis – Two Units Per Tray

PT# 280000
Model: MSD-2_Dual-1U
Description: MSD-2 Dual 1U Rackmount Chassis

  1U Rackmount Chassis – One Unit Per Tray

PT# 274000
Model: MSD-2_Single-1U
Description: MSD-2 Single 1U Rackmount Chassis

  Standalone Chassis

PT# 272000
Model: MSD-2_ Standalone
MSD-2 Standalone Chassis

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
Optional Accessories 1) Spare Data Center Fuses
A) 160ma Fuse, Qty (2) Part # 714000
B) 80ma Fuse, Qty (2) Part # 714001