BLACK BOX MD833C-R7 Analog Sync/Async V.32 Modem – Dial-up or Leased-Line, Rack-mount

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BLACK BOX MD833C-R7 Analog Sync/Async V.32 Modem – Dial-up or Leased-Line, Rack-mount

The BLACK BOX MD833C-R7 is a universal, multimode multispeed modem which utilizes the latest in Digital Signal Processing technology to provide flexible, high-performance data communica­tions. The BLACK BOX MD833C-R7 is a diagnostic modem that accommodates flexible installation requirements, rapid setup, continuous DTE and telephone line status repor­ting, as well as comprehensive diagnostics to minimize downtime.


The BLACK BOX MD833C-R7 operates at 14.4K bps full duplex over the standard 2-wire Public Switched Telephone Net­work (PSTN) and over 2-or 4-wire unconditioned leased lines. Fallback rates of 12.0K 9600, 7200, 4800, 2400, 1200, 1200/75, 600 and 300 are also supported.  Additionally, the BLACK BOX MD833C-R7 supports CCITI V.13 for simulated half-duplex operation.


The BLACK BOX MD833C-R7 supports multiple modulation standards for installed base compatibility. At 14.4K, 12.0K, 9600, 7200 and 4800 bps the BLACK BOX MD833C-R7 is compliant with CCITI Recommendation V.32bis. At 14.4K and 12.0K the BLACK BOX MD833C-R7 is compliant with the CCITI Recommendation V.33. At 9600 and 4800 bps the ALX V.32/14.4m is compliant with the CCITI Recommen­dation V.32. At 4800, it is compatible with Bell 208 A/B modems. At 2400 bps, it is compliant with CCITI V.22bis and at 1200 and 300 bps, it is compatible with Bell 212A and Bell 103 modems, respectively.


The BLACK BOX MD833C-R7 is compatible with Black Box’s Series 431 and AMS Network Management System. The diagnostic interface to the BLACK BOX MD833A-R7v allows centralized configuration, status monitoring and diagnostic control over a network of BLACK BOX MD833C-R7 Modems in any of its operating modes: dial line, leased-line or a combination of both. BLACK BOX MD833C-R7 reports on the con­dition of the attached DTE device and telephone line to the AMS Network Manager Controller or other data terminal equipment meeting the flexible requirements of the diagnostic interface. The simple command language utilized by the diagnostic interface allows for flexible user customization to meet network management objectives.


The BLACK BOX MD833C-R7 supports an automatic dial backup feature for leased-line applications. The BLACK BOX MD833C-R7 monitors the received carrier level and ljne quality and in the event performance drops below the selected threshold, will place a single dial call to the remote BLACK BOX MD833C-R7 via the PSTN. Automatic lookback allows communications to be returned to the leased line when conditions permit. Time-controlled dial backup is available as an option in units with an on-board real time clock (RTC).


Automatic call origination is provided by the BLACK BOX MD833C-R7 via a Hayes compatible or CCITI V.25bis compliant auto-dialer. The Hayes® emulation mode allows the BLACK BOX MD833C-R7 to interface with a computer running intelligent communications software written to drive a Hayes® -style autodial modem. The CCITI V.25bis auto­dialer is compatible with asynchronous and synchronous serial call origination standards.


The BLACK BOX MD833C-R7 supports MNP® (Microcom Networking Protocol) and CCITI V.42bis provides end-to­end error correction and data compression between the BLACK BOX MD833C-R7 and another modem equipped with MNP® or V.42bis in the asynchronous operating mode. Error correction may be enabled in both dial and leased line operation.


Security operation is available with the BLACK BOX MD833C-R7 to screen incoming calls. The BLACK BOX MD833C-R7 can be programmed to callback or pass-through the in­coming caller after password validation. The BLACK BOX MD833C-R7 can also be programmed for transparent password protection in all operating modes by incorpora­tion of the security password into the handshake process.


The BLACK BOX MD833C-R7 provides soft setup for unit configuration. All Alliance modems incorporate a Liquid Crystal Display (LCD) and six front panel pushbuttons. Ths allows one method of unit configuration from the front panel, alleviating the need for internal switches. The op­tions once selected are stored in nonvolatile memory (EEPROM). Another method of setup is provided through the diagnostic interface. A simple command language is utilized that allows local and remote configuration of the BLACK BOX MD833C-R7 over the diagnostic interface.


Fully featured diagnostics are included for rapid prob­lem isolation and downtime minimization. CCITT V.54 tests plus self-tests can qe initiated from the unit's front panel, DTE interface or diagnostic interface. The BLACK BOX MD833C-R7 supports Analog Loopback (Loop 3), Analog Loopback Self-test, Analog Loopback Self-test with Errors, Remote Digital Loopback (Loop 2), Remote Digital Loop­back Self-test. In addition to diagnostic tests, the BLACK BOX MD833C-R7 provides numerous status displays the monitoring of the DTE interface and telephone line conditions.  These status displays are available on the unit's front panel as well as remotely through the diagnostic interface.


The BLACK BOX MD833C-R7 Modems are available in both stand-alone and rack-mount configurations. The units utilize a common base and are therefore interchangeable. For


117 VAC and -48 VDC applications, the rack provides mass termination connectors or optional single line breakout cards for the telephone line interface. Separate DTE interface connectors are provided as well on the rack's motherboard. Hot insertion is permitted and rapid swapping of rack-mount cards is accommodated, thus minimizing the time and cost of reconfigurations as in­stallation and maintenance requirements dictate.

Additional information

Weight 3.00 lbs
Dimensions 9.00 × 6.00 × 4.00 in


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Multimode, Multispeed Operation for Installed Base Compatibility
• Full-Duplex Operation Over a Single Dial Line, 2-wire and 4-wire private lines
• Simulated Half-Duplex operation
• Hayes® and CCITI V.25bis Auto-dialers
• Security operation
• MNP® Class 5 and CCITI V.42bis for Asynchronous Error Correction and Data
• Soft Setup Configuration
• CCITI V.54 Diagnostics
• Stand-Alone and Rack-Mount Configuration
• Optional Time/Day/Date-Controlled Dial Backup (RTC units)


CCITT V.32bis at 14.4K, 12.0K, 9600, 7200 and 4800 bps
CCITT V.33 at 14.4K and 12.0K bps CCITT V.32 at 9600 and 4800 bps
Bell 208 A/B at 4800 bps
CCITT V.22bis at 2400 bps
Bell 212A at 1200 bps
Bell 103 at 0-300 bps
Alternate Fallback Capability
CCITT V.22 at 1200 and 600 bps
CCITT V.21 at 0-300 bps
CCITT V.23 at 1200/75 bps

Data Rates

600-14.4K bps, asynchronous or synchronous
300, 1200/75, 19.2K and 38.4K bps, asynchronous only

Data Format

Asynchronous: 8,9, 10, or 11 bits, serial, binary

Synchronous: Serial, binary


Full-duplex over 2-wire dialup lines (0-19.2K bps), and over 2-or 4-wire leased lines (4800-19.2K bps)
Simulated half-duplex operation with CCITT V.13


QAM at 14.4K, 12.0K, 9600, 7200 and 4800 bps echo cancel, full duplex (Trellis coded or non-coded at 9600 bps)
8 phase DPSK (Bell 208 mode)
QAM at 2400 bps band-split, full duplex;
DPSK at 1200 bps band–split, full duplex
FST< at 0-300 bps band-split, full duplex


Automatic adaptive equalization
Selectable compromise equalization (4 types)


Terminal: RS-232(/D, CCITT V.24N.28
Telephone Line: Dialup – 8-pin modular jack with A/A1 & Ml/MIC
                           Leased – 6-pin modular jack

Line Requirement


Transit Timing

Internal, External or Slaved

Transmit Level

Dial: Permissive (RJ11C) or
        Programmable (RJ415/RJ45S)
Leased: 0 to -15 dBm selectable

Power Consumption

13 watts

Current Draw

.11 amps

Heat Generation

44 BTU/hr

FCC Compliance

Complies with FCC Part 15 Class A radio frequency radiation limits
FCC Part 68 Registration Number: ABE976-17652-MD-E
Ringer Equivalence: 0.8B


Ambient temperature: 0 to 50°C (32 to 122°F)
Storage temperature: -20 to 70°C ( -4 to 158°F)
Relative humidity: 10 to 95% at 24°( (75°F) noncondensing


Width: 9.7 inches (24.6 cm)
Height: 2.5 inches (6.35 cm)
Depth: 10.1 inches (25. 7 cm)


Stand Alone: 4 lbs. 2 oz. (1.87 kg.)
Rack Mount: 2 lbs. (.91 kg.)