Burr-Brown LDM70 Industrial Limited-Distance Modem

Burr-Brown LDM70 Industrial Limited-Distance Modem is a fully isolated RS-232 modem designed to extend serial links across industrial facilities while protecting equipment from ground loops and electrical noise. The LDM70 provides complete isolation with optical couplers and a DC-DC converter, supports RS-232 data rates from 0 to 57,600 baud, and is optimized for video display terminals and other RS-232 devices in harsh environments. Distances vary with baud rate: up to 3 miles (about 5 km) at 9,600 baud, roughly 1 mile (1.7 km) at 19,200 baud, and about 0.5 miles (0.8 km) at 57,600 baud. It uses two DC-continuity twisted-pair conductors and supports four-wire full duplex or two-wire simplex operation, with Data Terminal Ready and Carrier Detect handshake available without extra wires. The unit includes surge protection and four LED diagnostic indicators, and it comes in a rugged aluminum enclosure compact enough to mount on the back panel of VDT units, saving space while keeping the serial link isolated in industrial environments.