Multi-Drop RS-232 Multiplexer

Multidrop multiplexing for up to 32 ports and 32 remote sites

Host Site SRX Multiplexer Remote Site SPL Multiplexer


Port Specifications
Network Specifications
Operating Modes
Network Management Port
Network Management Port Commands


How To Order


The DCB Multidrop Multiplexer Firmware Cartridge is used in the DCB SRX multiplexer at the host site, and in DCB SPL multiplexers at remote sites. Up to 32 total channels can share a single multidrop line for up to 32 remote sites. The DCB multiplexers with the multidrop firmware cartridge installed can run network speeds up to 64 Kbps. The decreasing costs of 56 Kbps multipoint lines make them a very attractive alternative to multiple point-to-point lines. When using a 56 Kbps multidrop line, the DCB multidrop configuration provides the user with a response time equal to point-to-point links.

The DCB SRX multiplexer is used at the host site. Configuration and diagnostic testing are performed through the Network Management Port. Any asynchronous terminal or PC with a serial communications program can be used to access the Network Management Port. All Network Management Port functions are accessed through the DCB easy menu system. Configuration is as simple as choosing a speed, parity, flow control and remote site/port for each host port activated. The DCB SRX is available with 8, 16, 24 or 32 ports.

The DCB SPL multiplexer is used at the remote sites. Ports are configured for speed, parity and flow control. The DCB SPL is available with 2 to 14 ports in 2 port increments. A remote site can have more than 14 ports through the use of multiple SPL multiplexers with a DCB modem sharing unit. Remote units are set to a unique address to identify each remote site separately.
The DCB multidrop protocol is optimized to make user response as fast as possible.

The host automatically measures the remote response times and independently sets each site's response timeout to the minimum possible delay. Remote units can respond to polls as soon as recognizing their address instead of waiting for poll completion.

The DCB multidrop multiplexer firmware allows you to take advantage of the significant cost savings of 56 Kbps multidrop lines for your asynchronous terminal applications. This savings can be yours without sacrificing user response time performance.

Multidrop Asynchronous Statistical Multiplexing
Host: 8, 16, 24 or 32 channels
Drops: 2 to 14 channels each in 2 channel increments
Up to 32 remote drops
Port Specifications
Data Format:
1 Start bit
1 Stop bit
10 bits total
8 Data bits including parity if used
Rates: 300, 1200, 2400, 4800, 9600 & 19,200 bps individually selectable per port
Interface: CCITT V.24, RS-232-D
Buffering: 64K dynamically allocated
Flow Control: Set on an individual port basis
Clear to Send
Busy High
Busy Low
Host: RJ-45 (8-wire)
Drops: DB-25 female
Network Specifications
Rates: Follows modem clock to 64 Kbps synchronous
Interface: CCITT V.24, RS-232-D
Error Correction: Automatic retransmission
Host: RJ-45 (8-wire)
Drops: DB-25 male
Cables: Host Network to modem/DSU cable supplied
Operating Modes
Normal on-line
Network loopback
Indicators (front panel)
Host: Power, Activity, Line Error, Modem Ready, Option
Drops: Power, Transmit Condition, Receive Error, Multiplexing, Test, Tx/Rx for each port
Host: Front panel push buttons for Next, ->, INCR, OK, RESET
Drops: Front panel DIP switches for address, port speed & flow control, push button for Reset
Network Management Port
Interface: CCITT V.24, RS-232-D
Host: RJ-45 (8-wire)
Drops: DE-9 female
Network Management Port Commands
Show: Map, Configuration, ID, Status
Configure: Map, Port, ID, Timing
Flow Control
Test Tools: Test message, Remote test loop, Capture, Copy, Monitor Tx, Monitor Rx Executive Parity Reset
Set Time
Power Requirements: 120 VAC, 30-43 Watts, .25-.36 Amps
Host 8 or 16 channel; Drop 2, 4 or 6 channel 10 1/4" x 9 3/4" x 2 1/4"
Host 24 or 32 channel; Drop 8, 10, 12 or 14 channel: 10 1/4" x 9 3/4" x 4 1/2"
Host: Internal DSU/CSU with 56, 19.2 & 9.6 Kbps speeds
19" rackmount cage & power supply
Drops: DCB MSU for more than 1 multiplexer at a single remote drop


How to Order


SRX-08 8 Port Host or Remote Multiplexer $ 1,695
SRX-16 16 Port Host or Remote Multiplexer $ 2,795
SRX-24 24 Port Host or Remote Multiplexer $ 3,995
SRX-32 32 Port Host or Remote Multiplexer $ 4,995
SR-EC8 8 port expansion kit $ 1,200
SR-DSU Integral 56 Kbps DSU/CSU $ 700
SR-144Integral 14,400 bps v.33 modem $1,400

Above Prices INCLUDE one firmware load each.
Order additional firmware packages below.

SRX-MD Host multidrop firmware $ 500
SRX-MH64Dual host multidrop firmware $1,000
SRX-FR Frame Relay firmware: Point-to-Multipoint Host $ 500


SPL-02 2 Port Host or Remote Multiplexer $795
SPL-04 4 Port Host or Remote Multiplexer $ 1,195
SPL-06 6 Port Host or Remote Multiplexer $ 1,495
SPL-08 8 Port Host or Remote Multiplexer $ 1,995
SPL-10 10 Port Host or Remote Multiplexer $ 2,295
SPL-12 12 Port Host or Remote Multiplexer $ 2,695
SPL-14 14 Port Host or Remote Multiplexer $ 2,995

The multidrop firmware Option is required for each remote. It is free when ordered with the unit.

SPL-MD Additional remote multidrop firmware option $500

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