FEATURES

• Multistandard: V.34, V.33, V.32bis, V.32, V.29, V.27ter, V.27bis, V.26bis, V.26, V.22bis, V.22, V.23 and V.21. 
• Automatic Leased Line Restoral with Line Acceptance and real-time clock control. 
• V.25bis and Synchronous HDLC, SDLC and BSC for both V.25bis and AT-commands. 
• 8 stored configuration profile locations. 8 predefined customizable settings 
• AutoBaud for automatic detect of asynchronous data rates from 75 up to 38.4 Kbps 
• AutoMode for automatic selection of ITU-T V.34, V.32bis, V.32, V.22bis, V.22, V.23 and V.21 modes on dial-up operation 
• Error Correction as per ITU-T V.42 LAP-M and MNP4 for reliable asynchronous communication 
• Data Compression as per ITU-T V.42bis and MNP5 for high asynchronous troughput 
• Simulated switched carrier operation as per ITU-T V.13 for ITU-T V.34, V.32bis, V.32, V.22bis and V.22 operation in half-duplex environments. 
• Automatic Rate Change (ARC) for continuously optimising the transmission rate to ensure maximum throughput
• Password and Callback security to control unauthorised access to the attached DTE. Callback list of up to 100 numbers. 
• AutoLogon for automatic connection to password security modems
• MultiPoint operation to save leased line costs and Host-site ports 
• Adressed Remote Access for remote configuration and diagnostics wich offers a simple means of modem management. 
• Standalone version in compact desktop model with internal power supply.

OPERATION

Multistandard

The UDM-288.3 features the ability to interconnect with nearly every modem that is currently used on dial- up networks or leased lines: ITU-T V.34, V.32bis, V.32, V.33, V.29, V.27ter, V.27bis, V.26bis, V.26, V.22bis, V.22, V.23 and V.21. The modem also operates the Bell 224, 212A and 103 modes. This means that all your modem applications could be covered by one type of modem: the UDM-288.3. The UDM-288.2 operates all modem modes used on Dial-up or 2-wire lines: ITU-T V.32bis, V.32, V.29, V.27ter, V.27bis V.26bis, V.26, V.22bis, V.22, V.23, V.21 and Bell 224, 212A and 103 modes to support all full- or half-duplex applications on 2-wire connections. The UDM-288.1 supports all 2-wire full-duplex applications by operating ITU-T V.32bis, V.32, V.22bis, V.22, V.23, V.21 and Bell 212A and 103 modes.
 

Automatic Rate Change

The Automatic Rate Change feature allows the UDM-288 to automatically change data rate in order to optimize user data throughput. With the Automatic Rate Change feature enabled, the modem continuously monitors the signal quality and selects the appropriate transmission rate to minimize errors and maximize the throughput.
 

Leased Line Restoral with Line Acceptance

On 2- or 4-wire leased line operation the UDM-288 can utilize its dial-up network capability to restore service when loss of connection on the leased line occurs. When the performance over the leased line drops below unacceptable levels the UDM-288 automatically establishes the connection over the dial-up network.

Different modulation modes can be selected for leased line and restored links. For example a V.33 connection may be restored on the dial-up line in V.32bis or any other full-duplex 2- wire mode. During dial-up line operation the UDM-288.3 continuously tests the leased line by means of an interactive V.19 type of data exchange. When the leased line becomes operative again and is of acceptable (user-defined) quality, connection over the leased line is automatically re-established. On the other models, return to leased line is controlled by user-defined timers.

The restoral operation of the UDM-288.3 can be enabled under control of a real-time clock in order to prevent unnecessary telephone connection costs at times when the modem connection is not in use. Restoral through the dial-up network or return to leased line can also be manually initiated by means of the DATA/PSTN button on the front panel.
 

Synchronous Applications

The UDM-288 supports a range of synchronous data rates from 1200 bps to 28.8 Kbps. The transmit timing source is selectable to be internal, externally supplied, or slaved to the receive timing. Automatic mode selection between ITU-T V.34, V.32bis, V.32, V.22bis and V.22 modes is offered as a standard feature. Automatic selection between e.g. ITU-T V.32 and V.26bis modes or other combinations can be supplied as an option. 

Simulated switched carrier operation is supported for applications where the DTE requires a half-duplex V.24 control. This feature enables the use of V.32bis or V.32 high-speed data rates in half-duplex applications which are found in many IBM environments. 

In multipoint applications the UDM-288 offers an AntiStreaming time-out which automatically drops RTS after a user defined time. This prevents multipoint networks from being "hung-up" by wrongly configured or defective DTEs. 

The UDM-288 supports both bit synchronous and character oriented protocols such as HDLC, SDLC,BSC or ISO 1754 accepting ASCII and EBCDIC character sets. Both V.25bis and AT-commands are accepted simultaneously. This makes the UDM-288 compatible with a.o. IBM AS/400, System 36/38 and 3745 FEP's and offers the use of the well known "AT" commands in various synchronous environments.
 

Asynchronous Applications

The UDM-288 supports asynchronous DTE speeds from 75 bps up to 115.2 Kbps. In AT-command mode the UDM-288 offers the AutoBaud feature that automatically configures the interface to the data rate of the connected terminal or computer. For dial-up operation the UDM-288 can be configured to automatically detect ITU-T V.34, V.32bis, V.32, V.22bis, V.22, V.23 and V.21 modes. This enables dial-in from the dial-up network for example to create a multistandard gateway to a computer system or digital network.

For errorfree transfer of asynchronous data the UDM-288 features the LAP-M and MNP 4 error control protocols as per the ITU-T V.42 recommandation. The UDM-288 will automatically adapt to the protocol that is supported by the remote modem.

The UDM-288 is fully compliant with the MNP 5 and ITU-T V.42bis data compression protocols for improved asynchronous throughputs. V.42bis enables a theoretical compression ratio of up to 4:1.
 

Configuration

Configuration sets of the UDM-288 may be saved in up to 8 stored profiles. One of the profiles can be selected as active on power-up by means of an AT-command or by means of dipswitches. 8 sets of common used applications are preprogrammed as default profiles. If none of these profiles is appropriate to your application, they can be customized and then saved as stored profiles.
 

Remote Access and Configuration

The Remote Access feature allows the UDM-288 to be controlled and configured from a remote site through the dial-up or leased line. The remote modem may basically be of any full-duplex type though Error Correction is preferred. Remote configuration is performed in the same way as local configuration. Up to 127 different access codes may be programmed. This enables individual configuration and modem management in for example network tail-circuits. Apart from configuration all status information of the remote modem on operating mode, line quality, receive level, round trip delay, data rates and V.24 interface is available.
 

Security Features

Password security offers an additional level of security to the system connected to the UDM-288. Before connection to the computer is enabled, a valid password must be received from the remote system. After three unsuccessful attempts the UDM-288 will disconnect the call, thus enabling other users to make connection.

In combination with password security on the remote side, Automatic Log-on provides automatic access to the remote system. 

With Call Back Security enabled, users dialling in to the UDM-288 will have to issue an identification by means of a password. After positive verification, the UDM-288 will disconnect the call, automatically dial back and enable the connection to the computer. The UDM-288 can store up to 100 IDs and call-back numbers.
 

Front Panel

The UDM-288 offers a front panel with status LEDs and push buttons for Data/Talk operation and the selection of local analogue or remote digital loops. The LED indicators signal Modem Ready and PSTN operation and the status of the V.24 Transmit Data, Receive Data, Data Terminal Ready, Request To Send, Clear to Send, Data Carrier Detect and Loop Test signals. 
 

TeleTest

On the rear panel the UDM-288 is equipped with a swith that forces the modem into teletest mode. In this mode an engineer can remote acces the modem to check performance or program new user profiles. 

TECHNICAL SPECIFICATIONS 

• Modem modes 

- V.34 28800 bps down to 2400 bps full-duplex on PSTN and leased lines
- V.33 14400, 12000 bps full duplex on 4-wire lines 
- V.32 bis14400, 12000, 7200 bps full-duplex on PSTN and leased lines 
- V.32 9600, 4800 bps full-duplex on PSTN and leased lines 
- V.29 9600, 7200, 4800 bps half-duplex on 2-wire or PSTN 
- V.29 9600, 7200, 4800 bps full-duplex on 4-wire lines 
- V.27 ter4800, 2400 bps half-duplex on PSTN 
- V.27 bis4800, 2400 bps full-duplex on 4-Wire lines 
- V.27 bis4800, 2400 bps half-duplex on 2-Wire lines 
- V.26 bis2400, 1200 bps half-duplex on PSTN 
- V.26 2400 bps (alt.A and alt.B) full-duplex on 4-wire lines 
- V.26 2400 bps (alt.A and alt.B) half-duplex on 2-wire lines 
- V.22 bis2400, 1200 bps full duplex on PSTN and leased lines 
- V.22 1200 bps full-duplex on PSTN and leased lines 
- V.23 1200 bps full-duplex on 4-wire lines 
- V.23 1200/75, 75/1200 bps duplex or 1200 bps half-duplex on PSTN 
- V.21 300 bps full-duplex on PSTN and leased lines 
- Bell 224 2400 bps full-duplex on PSTN and leased lines 
- Bell 212A 1200 bps full-duplex on PSTN and leased lines 
- Bell 103 300 bps full-duplex on PSTN and leased lines
 

• Async/Sync convertor

- Async/sync conversion as per ITU-T V.14 selectable on all synchronous modem modes

• Autodial and configuration 

- V.25bis and AT-commands 
- All command modes both Async and Sync (HDLC, SDLC, Bisync) 
- Selectable originate or answer carrier in dial mode

• Autoanswer 

- Conforms ITU-T V.25 
- Selectable answer or originate carrier in answer mode 

• Half-duplex and MulitiPoint applications

- Selectable AntiStreaming timer 
- Selectable echo protect sequence on V.26 and V.27 modes 
- Selectable long train sequence on V.27 modes 
- Simulated switched carrier as per ITU-T V.13 

• Errorcorrection/Datacompression 

- ITU-T V.42 errorcorrection
- ITU-T V.42bis datacompression 
- MNP4 errorcorrection 
- MNP5 datacompression 

• DTE Interface 

- compatibily: ITU-T V.24/V.28, ISO 2110 
- supported circuits:102, 103, 104, 105, 106, 107, 108/1, 108/2, 109, 111, 113, 114, 115, 125, 
  133, 140, 141, 142 
- synchronous data:1.2, 2.4, 4.8, 7.2, 9.6, 12.0, 14.4, 16.8, 19.2, 21.6, 24, 26.4, 28.8Kbps 
  (+/- 0.01%) 
- synchronous timing:internal, external or slaved to receiver
- asynchronous data:0..300 bps, 1.2, 2.4, 4.8, 9.6, 19.2, 38.4 Kbps (+/- 2.5%) 
- async. data format:10 or 11 bits even, odd or no parity for command modes 8, 9, 10 or 11 bits
  for data transmission modes 
- flowcontrol: both DTE to DCE and DCE to DTE flowcontrol "software" control: Xon/Xoff or user
  defined characters "hardware" control: circuit 106 and circuit 133 (105)

• Diagnostics

- Testloops: DL, RDL and AL as per V.54 loop 2 and loop 3 
- Automatic self check on power-up 
- Extended self check
- Received signal level 
- Signal to noise ratio 
- Round trip delay 
- Eye pattern generator
- Remote Diagnostics and status information 

• Line Requirements 

- ITU-T M.1040, M.1025 and M.1020 or unloaded lines 

• Line Transmission Characteristics 

- Impedance: Network Reference Impedance or 600 Ohms 
- Return loss: better than 25 dB 
- Symmetry: better than 70 dB 
- Noise and spurious:below -75 dBm 
- Receive levels:-5 to -43 dBm, thresholds at -23, -33 or -43 dBm 
- Transmit levels:selectable to -15 dBm on Leased Lines and PSTN in 2dB steps.

• Power Supply 

- Operating voltage range: 190 to 245 Volts
- Frequency range: 45...65 Hz 
- Power consumption:12 Watts max.

• Environmental Characteristics 

- Operation temperature:0 to 50C (95% humidity non-condensing) 
- Storage temperature:-50 to +700C 
- EMI/RFI emissions:conforms CENELEC EN 55022 and VDE 878 Physical Characteristics 
- Dimensions: 240 x 160 x 54 mm (L x W x H) 
- Weight:1.2 Kg