Statistical Multiplexer - SR-04

Low Cost 4 channel multiplexer, available with TDM Firmware Option

  • Optional internal 56/64 Kbps DSU/CSU
  • Optional frame relay FRAD firmware
  • Optional TDM, Time Division Multiplexing firmware
  • Port speeds to 57.6 Kbps
  • Asynchronous composite to 115.2 Kbps
  • Synchronous composite to 128 Kbps
  • Network Management Port
  • Remote set up and testing
  • Composite is full duplex asynchronous, synchronous, analog modem (leased line or dial-up) or digital
  • 4 asynchronous channels
  • Works well with spread spectrum radios
  • Test message generation
  • "Data Scope" functions to allow monitoring of any data port
  • "Copy Command" for remote training
  • Composite link is error corrected


Port Specifications
Network Specifications
Operating Modes
Indicators (front panel)
Network Management Port
Network Management Port Commands





The SR-04 statistical multiplexer concentrates 4 asynchronous channels over a synchronous or asynchronous composite. All port parameters are set with an asynchronous terminal connected to the network management port or port 1. Set-up procedures are menu driven and fully explained on screen. All configuration parameters are battery supported through power outages.

The asynchronous ports can be individually set for speeds to 57.6 Kbps. Hardware (CTS/Busy high or low) or software (Xon/Xoff even, odd, mark, space or transparent) flow control is also set on a port by port basis.

The SR-04 composite is asynchronous or synchronous full duplex lines either analog or digital. The composite can be run at speeds up to 128 Kbps synchronous or 115.2 Kbps asynchronous. The composite may be used through analog leased lines, dial-up modems, ISDN TAs, radio modems, digital DSUs, or equivalent links.

The network management port includes local and remote configuration commands. The Show Configuration Commands allow the system manager to view the configuration settings of both the local and remote SR-04 Multiplexers. Network management features include port and composite loopbacks, capture of a remote or local port, send a test message to an individual local or remote port, set multiplexer ID for node identification and a built-in "data line monitor" which allows the monitoring of the transmit or receive lines at the local multiplexer. A unique feature of the SR multiplexer is the Copy Command. This command allows a trainer at the host site to "copy" any local or remote port to view exactly what the user is entering. This feature can save thousands of training dollars by eliminating travel expenses.

The SR-04 multiplexer has a side panel access for firmware cartridge installation. This feature simplifies installation of upgrades for new features and functions.

The SR-04 is compatible with virtually all async terminal-printer/computer links. You can save thousands of dollars by concentrating your terminals on one line while delivering top performance. In addition, with features like the loopback, test message, ID, monitor and copy commands, you can take charge of your network like never before.

The SR-04 can be provisioned as a time division multiplxer(TDM) by including the free TDM-4 firmware. Using it as a TDM insures faster throughput for time-critical protocols such as mirrored bit. Normal TDM rules apply (aggregate speed must be as fast enough to pass the sum of all active port speeds).

A one port version is available for applications where the features of the SR series are required at a single port remote site. It is normally used in SMD (SCADA Mux) or SRX-SR multi-point frame relay systems.

Asynchronous Statistical Multiplexing
Time Division Multiplexing with TDM-4 firmware
4 channels
All ports can be 57,600 bps
Port Specifications
Data Format
1 Start bit
8 Data bits including parity if used
1 Stop bit
10 Bits total
Rates: 300, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57,600 bps individually selectable per port
Interface: CCITT V.24, RS-232-D
Connectors: RJ-45 (8-wire)
Buffering: 64K dynamically allocated
Port Flow Control: Set on an individual port basis
Clear to Send
Busy High
Busy Low
Network Specifications
Rates: Follows modem clock signals to 128 Kbps synchronous, 115.2 Kbps asynchronous
Interface: CCITT V.24, RS-232-D
Connector: RJ-45 (per EIA/TIA 561 spec for RS-232 in a modular 8 position connector)
Error Correction: Automatic retransmission
Network to modem/DSU cable included
Operating Modes
Normal on-line multiplexing
Network loopback
Indicators (front panel)
Power, Multiplexing, Receive Error, Modem Ready, Option, Port 1 Setup, Loopback
Network Management Port
Interface: CCITT V.24, RS-232-D
Connector: RJ-45 (8-wire)
Can be mapped to Port 1
Network Management Port to terminal cable included
Network Management Port Commands
Help Screen
Remote Test Loop
Monitor Transmit
Monitor Receive
Network Loopback
Flow Control Active
Set Time

Show Configuration
Show Network
Configure Ports
Port Loopback
Device Type
Capture Port
Copy Port
Send Test Message
Activity Counters
Power requirements: 120 VAC, 30-43 Watts, .25-.36 Amps
10 1/4" x 9 3/4" x 2 1/2"
Operational Temperature: -40 to +75 C
56 Kbps internal DSU/CSU

Rear view of DCB SR-04 Multiplexer


How to Order Call Us at 800-432-2638!

SR-04 4 (async) Port Multiplexer $ 775
SR-DSU4 Internal 56/64 Kbps DSU for SR-04 $ 325
SR-01 1 (async) Port Multiplexer $ 500
SR-FR Firmware to make SR-04 a 4 port async frad
(Free when ordered w/unit)
$ 500
TDM-4 Firmware to make SR-04 a 4 port time division multiplexer
(Free when ordered w/unit)
$ 500

Data Comm for Business Inc.
2949 County Road 1000 E
Dewey, Il 61840
Voice: 217-897-6600
Toll Free: 800-4-DCB-NET
Toll Free: 800-432-2638
Email: Contact Page
Fax: 217-897-8023
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