Comtech EF Data CRS-300 1:N Redundant Modem Switch

  • Automatic or manual redundancy for 1:10
  • Slaved switches available
  • Supports a wide range of modems
  • Provides single point remote M&C

Comtech EF Data CRS-300 1:N Redundancy Switch

The CRS-300 1:10 modem redundancy switch provides fully automatic or manual redundancy for the following modems: CDM- 570/570L, CDM-600/ 600L, CDM-625, CDM-Qx/QxL, CDM-700, CDM-710, and SLM-5650A.

The protection system consists of a maximum of 10 traffic modems, a redundant modem, and the CRS-300 redundancy switch. Two companion (slaved) 1:N switches are also available: the CRS-280/ 280L IF switch and the CRS-350 ESC switch. The IF switch is used in multiple transponder applications. The CRS-350 is used for open network ESC redundancy switching.


The CRS-300 supports a wide range of terrestrial data interface types including: EIA-422/530, V.35, EIA-232, LVDS, G.703 (balanced or unbalanced), ASI, 10/100/1000 Ethernet and HSSI. In many cases, each traffic modem can have a different terrestrial data interface types.

Key Reliability Features

  • Twin, independent AC or DC power supplies
  • Passive backplane for signal path
  • Non-interruption of normal traffic upon power failure
  • Non-interruption of user data when other traffic modem Interface circuit cards are removed
  • Data and clock provided to the redundant modem when in Bridge Mode
  • Programmable holdoff times to backup or restore
  • Audible alarm programmable to activate, based on various changes in status
  • Provides single-point remote Monitor and Control (M&C) to switch and traffic modems
  • Simplified configuration and control
  • 2 line x 24 character Vacuum Fluorescent Display
  • Front panel keypad
  • LED system status display showing unit and modem status, online/offline status, and bridge status

Super Functionality

The configuration of each traffic modem is stored in the CRS- 300 controller. This information is used to program the redundant modem if the traffic modem fails. The modem information is copied to the controller through a serial cable.

The CRS-300 also controls the traffic and redundant modem IF output. All modem outputs are ON if the CRS-280 or CRS-280L IF switch is used in the system. The downlink path through the CRS-280/ CRS-280L is completely passive.

External monitor and control may be connected to the CRS-230 controller board. The CRS-300 and each traffic modem may be monitored or controlled through this remote serial interface.

The data and clock signals to and from a traffic modem are routed through a Traffic Modem Interface (TMI) via a set of relays. This allows the data signals to pass directly through to the traffic modem in the event of a power failure. If the system’s power supplies are lost, or if a TMI carrying traffic is removed, no interruption of traffic occurs.

The Bridge Mode may be used to verify the user data on a specific traffic modem. The redundant modem locks to the traffic modem receive IF input signal. The operator can program a delay interval for the backup modem to wait before coming online when a traffic modem failure occurs.

Modular Construction

The redundancy switches are modular in construction. All replaceable modules insert into slots in the back panel, including the controller, Traffic Modem Interfaces (TMIs), Redundant Modem Interfaces (RMIs), and Power Supply Units (PSUs).

Power consumption is so low, even for fully populated units, that no fan cooling is required.

More Information
Country of ManufactureUnited States
ManufacturerComtech EF Data
Input Power100 - 240 VAC
Warranty2 Years
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