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Black Box Corporation • 1000 Park Drive • Lawrence, PA 15055-1018 • Tech Support: 724-746-5500 • www.blackbox.com • e-mail: info@blackbox.com
V.35 2-WIRE SHORT-HAUL MODEM
Key Features
For sending sync or async data.
2-wire, twisted-pair operation.
Transmit speeds up to 38.4 or 128 kbps.
Distances up to
3.4 miles (5.5 km).
Full-duplex operation using “echo cancellation.”
Performs local analog loopbacks and local and remote digital loopbacks.
Generates bit error rate test patterns.
Isolation transformer guards versus AC or DC overvoltages.
The BLACK BOX® V.35 2-Wire Short-Haul Modem provides a
simple way to send your data at short distance over telco lines. The modem operates full-duplex synchronously over a single 2-wire twisted pair, at selectable data rates from 600 bps up to 128 kbps, or asynchronously up to 38.4 kbps.
The short-haul modem incorporates interface circuits for the terminal or computer, an adaptive echo-canceler, an automatic adaptive equalizer, a modulator, and a demodulator. The adaptive equalizer provides noise immunity and high performance over low-quality lines.
The modem uses 2B1Q line coding and provides an operating range of up to 3.4 miles (5.5 km) over 26 AWG twisted-pair wire— no matter what data rate is used.
The modem also couples to the telephone line through an isolation transformer that protects against AC or DC overvoltages.
The protection circuitry enables the unit to survive even if DC is connected to the line accidentally.
Full-duplex operation uses echo cancellation. You need only to set one modem to be a master and the other to be a slave.
Internal DIP-switch controls enable you to configure the V.35
2-Wire Short-Haul Modem to suit your application. To reconfigure the modem for a different type of operation, just reposition the switches.
The short-haul modem also features diagnostic capabilities, including local analog loopback and local and remote digital loopback. An operator at either end of the link can test both local and remote short-haul modems as well as the line itself. Control loopback with either the unit’s front-panel pushbuttons or signals passed through the DTE (PC, data terminal) interface. Pressing the front-panel Pattern button causes the local short-haul modem to send the remote unit a continuous Bit Error Rate Test (BERT) pattern. By performing these end-to-end tests, you can ensure link integrity and quickly find out which components
of your short-haul modem system are operating properly and which aren’t.
For monitoring and troubleshooting purposes, the short-haul modem has eight front- panel LEDs that inform you of the device’s operational status and activity. At a glace, you can tell whether the local and remote units are in sync, when the RTS signal from the DTE is high, when the local unit is transmitting or receiving data, when the modem detects an error in the BERT pattern, and more.
For your transmission line, we highly recommend using twisted- pair cable capable of supporting high data rates, especially Category 3 grade or better. For DTE-side cable runs, use straight- through-pinned cable that’s no more than 25 feet (7.6 m) long with an M/35 male connector for plugging into the V.35 2-Wire Short-Haul Modem.
NOTE: Must be used in pairs.
