The DCB DA-56 is a 56 Kbps DSU with an asynchronous interface. The async interface can run at speeds from 9600 up to 115,200 bps (speeds below 9600 bps can be provided for special applications). It operates in either point to point or multidrop mode. A companion model, the SR-01DSU, is available for supporting async devices over Frame Relay networks.

56 Kbps DSU
RS-232 interface up to 115.2 Kbps
“AT” command spoofingĀ 
Anti-streaming timer option
Ideal for async Internet over DDS
Reliable, high speed private line service alternative to dial up modems
Watchdog Timer

The DA-56 is easy to install and operate. Controls on the unit include the loopback push button switch, a switch to allow setup of the unit through the data port, a switch to select line driver mode or phone company clock, a switch to select RTS forced on or terminal controlled, and a switch for an anti-streaming timer. The anti-streaming timer is useful for multidrop applications where the remote terminals can keep RTS asserted and kill a multidrop line if the anti-streaming timer is not used. The minimum number of controls and comprehensive indicators of the DA-56 make installation and troubleshooting easy. Diagnostic aids built into the DA-56 include LED indicators and loopback capabilities.

A unique feature of the DA-56 is the ability to mimic a generic modem handshake. This special feature allows PCs to use their built in dial-up-networking function.


Rates: Async rates of 9600, 19200, 38400, 57600 and 115200 bps
Application: Point-to-point or multidrop
Watchdog Timer: Unit resets if 30 seconds elapses without DCD asserted
Indicators (front panel)
Power, Activity, Line Error, Modem Ready, Port 1 Setup, Loopback
Front panel push button for loopback
Rear panel accessible DIP switches for internal /DDS line timing, a switch for RTS forced on or terminal controlled, and an anti-streaming timer switch option
Setup via the async RS-232 port, activated by the front panel push-button, or setup via rear panel management port

Interface: DDS bipolar non return to zero
Telco connector: RJ48S, 8 position RJ connector
DTE Port: RS-232, V.24, speeds up to 115,200 bps DTE port connector: RJ-45 per EIA/TIA 561 Management port: RS-232 for configuring unit
Power requirements: 120 VAC,
60 Hz, 18 Watts
Operating Temperature: -40 to +70 C
10 1/4″ x 9 3/4″ x 2 1/4″