ECD » Sharing Devices » RS-232

 RS-232: Modem Sharing Devices MSD-4 AND MSD-8


Speed & ESD Enhanced


  • Interface - EIA RS-232, CCITT V.24, DB-25 Female Connectors
  • Data Rates - Synchronous or Asynchronous up to 128Kbps
  • Anti-Streaming - Automatic or Manual for unattended Circuit Restoral
  • Individual Subchannel Enable / Disable Switches
  • Visual Indication of Subchannel Activity
  • Receive Data - Broadcast to all Subchannels
  • Transparent to Data
  • Fully Cascadable
  • External Clocking
  • Sturdy Metal Enclosure
  • 110/220VAC Switch Selectable
  • +/- 15KV ESD Protection
  • Approvals - UL and CSA


The Modem Sharing Device (MSD) products consist of 4 and 8 port units. The MSDs provide 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's, up to eight 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 MSDs are protocol transparent at data rates up to 128Kbps. 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 MSDs incorporate 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 MSDs will provide in excess of 100,000 hours of reliable service.

The MSDs have a three year warranty and a 24 hour turnaround on warranty repairs.



Application Multiple Sync/Async terminal or DTE devices operating in a polled environment, to share one Modem
Capacity One to eight RS-232 Sync/Async devices
Interface EIA RS-232, CCITT V.24 using DB-25 female connectors, +/- 15KV ESD Protection
Data Rates Up to 128Kbps
Data Format Data transparent at all data rates
Timing External; from attached Modem
Anti-Streaming Automatic . . .Selectable time out intervals

Disable . . . . .Selectable via dip switch

Terminal Service Modes Scanning or Priority
Front Panel Indicators . . . Power, Transmit Data, Receive Data, Channel Active, Channel Stream

Switches . . . . Enable/Disable of each Subchannel

Power Source 100-120 to 200-220VAC @ 10%, 50/60Hz, 0.16/0.08A, external 110/220 volt select switch, IEC Power Inlet, (2) 5mm Fuses
Approvals UL and CSA
Environmental Operating Temperature . .32º to 122º F (0º to 50º C)

Relative Humidity. . . . . . .5 to 95% Non-Condensing

Altitude. . . . . . . . . . . . . ... .0 to 10,000 feet


MSD-4 and MSD-8

Height . . . . . . . . . . . . . . .1.75 inches (4.44cm)

Width . . . . . . . . . . . . . . . 13.35 inches (33.09 cm)

Length . . . . . . . . . . . . . . 9.00 inches (22.86 cm)

Weight MSD-4 and MSD-8 ......... 4.5 pounds (2.1 Kg)
Warranty Three Years, Return to Factory
Part: 101000
Description: 4 Port Modem Sharing Device

Model: MSD-8
Part: 102000
Description: 8 Port Modem Sharing Device

INCLUDED WITH EACH UNIT: 1) Operations Manual

2) U.S.A. Grounded Power Cord, Part #713015


1) Optional Power Cords

A) United Kingdom, Part #713016

B) Continental Europe, Part #713017

C) Other: Specify Country on Purchase Order

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