DV-1 56 Kbps Voice/Data Multiplexer

Table of Contents


The DCB DV-1 is a 56 Kbps DSU/CSU which provides one data and one voice channel over a 56 Kbps digital line. The data channel can operate at 9600, 19,200 or 38,400 bps and includes both a V.35 and an RS-232 interface connector. The voice channel will operate at 16 or 32 Kbps. Three voice interfaces are provided: a modular RJ-11 interface for a standard 2 wire telephone set; a modular RJ-11 interface for connection to a PBX station line; a modular RJ-45 interface for 4 wire E&M PBX tie line connections.


Data Port

Composite Port

Voice Ports




The following is included with each DV-1


Place the DV-1 in a clear area where you can reach the rear panel for setup and to connect the cables. The DV-1 has an external power supply that requires a properly grounded 120 VAC outlet.


Setup of the DV-1 is done using the rear panel DIP switches.


Connect the DV-1 to the phone line using the RJ-45 to RJ-45 cable provided. Connect the terminal device (multiplexer, LAN, host computer, controller) to the RS-232 or V.35 port of the DV-1. Connect the telephone, key system, PBX or phone line to the appropriate RJ voice port of the DV-1.



A 10-position DIP switch is located on the right hand side of the rear of the unit. This DIP switch is used to set the unit configuration. The switch positions are numbered 1 through 10 and their functions are as follows:

S1-1S1-2Voice Mode
UPUPDo not use this setting
UPDNTie Trunk4 wire E&M
DNUPTelephone SetTelset

S1-3S1-4Voice RateData Rate
UPUP16 Kbps19.2 Kbps
UPDN16 Kbps38.4 Kbps
DNUP32 Kbps9.6 Kbps
DNDN32 Kbps19.2 Kbps


S1-6Slave/Master Clock
UPSlave Clockdefault
DNMaster Clockuse for line driver mode only

S1-7RTS Mode
UPRTS Controlled by DTEdefault
DNRTS Forced on

S1-8CTS Mode
UPCTS Normaldefault
DNCTS Forced on

S1-9Async data length
UP9 Data bits
DN8 Data bitstypical for async operation

S1-10Enable/Disable Test Modes
UPTest Modes Enableddefault
DNTest Modes Disabledto prevent accidental test activation


Select Switch

The Select switch is located on the front of the unit and is used to select test modes. Pressing once selects Self Test. A second press selects Digital Loopback, etc. You must cycle through all four test modes to return to normal operation. Therefore, the switch must be pressed a total of five times to return the unit to normal operation.


The indicators on the front of the unit are divided into two groups; six status indicators on the left, four test indicators on the right.

Blinking RED - No Rx signal or bi-polar violations
Solid RED - Out of frame or out of service sent by telco
Blinking GREEN - Out of sync or control mode idle
Solid GREEN - In Sync normal operation
ON - valid data being received.
OFF - unit not in service or idle signal being received
ON - RTS is present from DTE device
OFF - no RTS from DTE device
ON - unit is in service and RTS is valid
OFF - out of service or no RTS
TxDFlashes when transmit data is present.
RxDFlashes when receive data is present.
Self Test
Flashes red while self test is in progress.
Flashes green when unit passes self test.
Digital Loop
Flashes when bi-directional digital loopback is selected.
ON indicates TELCO DSU loop active.
Line Loop
Flashes when local line loopback is selected.
ON indicates TELCO CSU loop active.
Remote Test
ON GREEN - other end sending remote test
Flashes red while awaiting remote test results.
Flashes green after valid response is received.

Interface Signals and Cabling

Telco Interface

Composite Port RJ-48S

1Transmit Data
2Transmit Data
7Receive Data
8Receive Data


Data Interfaces

RS-232 Interface DB-25S

2Transmit DataIN
3Receive DataOUT
4Request To SendIN
5Clear To SendOUT
6Data Set ReadyOUT
7Signal Ground------
8Data Carrier DetectOUT
15Transmit ClockOUT
17Receive ClockOUT
20Data Terminal ReadyIN

V.35 Interface M34 female

PinSignalSignal Source
BSignal Ground
CRequest to Send Terminal(unbalanced)
DClear to Send DV-1(unbalanced)
EData Set Ready DV-1(unbalanced)
FData Carrier Detect DV-1(unbalanced)
PTransmit Data A Terminal(balanced)
STransmit Data B Terminal(balanced)
RReceive Data A DV-1(balanced)
TReceive Data B DV-1(balanced)
YTransmit Clock A DV-1(balanced)
AATransmit Clock B DV-1(balanced)
VReceive Clock A DV-1(balanced)
XReceive Clock B DV-1(balanced)


Voice Interfaces

TelSet RJ-11


4W E&M Tie Line RJ-45

1Signal Ground
2EarControl signal to PBXThe printed manual is incorrect on this!
3TipReceive from PBX
4TipTransmit to PBX
5RingTransmit to PBX
6RingReceive from PBX
7MouthControl signal from PBXThe printed manual is incorrect on this!
8Station Battery

PBX Line RJ-11




Testing Self Test

Push the select button once. The Self Test LED will flash red and internally the transmitter is connected to the receiver. An internal test pattern generator runs a complete diagnostic on the unit. In about 5 seconds, the Self Test LED should change from flashing RED to flashing GREEN. Return to the normal mode by pushing the front panel button until the test LED is out. Digital Loop

Push the test button until the Digital Loop LED flashes. Internally, the unit is configured as below. This test allows the user to run a complete "round trip" test as shown below. Line Loop

Push the select button until the Line Loop LED flashes. The unit is internally looped. The user can now use a test set plugged into the TERMINAL connector to run tests. Functionally, this is the same as the Self Test except that the internal pattern generator is not used. Remote Test

Push the select button until the Remote Test light flashes. It will flash red until it detects an "OK" pattern from the remote unit. The Remote Test light will then flash green. The remote unit is in a remote test condition and a complete "round trip" test is being performed by the internal pattern generator. To end this test, push the select button one more time. Voice Testing

First verify that the DSU function of the DV-1 is operating, per the steps outlined above. If you are still unsure about the voice path, the easiest and most inexpensive troubleshooting begins with using a single line telephone at each end.

Set the DV-1 switch 1 down and 2 up for connection to a telephone. Plug a single line phone into the "Telset" connection at both ends. Pick up a phone at one end and it should ring at the other. When the phone is answered, an end to end voice path should now be established.


All DCB products are warranted to be free of defects in materials and workmanship for one year. DCB of Champaign, Inc. will repair or replace any equipment proven to be defective within the warranty period. All warranty work is F.O.B. Champaign, IL. This warranty is exclusive of abuse, misuse, accidental damage, acts of God or consequential damages, etc. DCB liability shall not exceed the original purchase price.

All equipment returned for warranty repair must be accompanied by a Returned Material Authorization (RMA) number. To receive an RMA number, call 217-352-3207 between the hours of 8 AM and 5 PM central time. Equipment must be shipped prepaid to DCB and will be returned at DCB's expense.