Black Box ME800A Async Short Haul Modem

The Black Box ME800A-R4 Async Short-Haul Modem is a rugged, standalone RS-232 modem designed to carry asynchronous serial data over CATx copper cabling by pairing two units to create a full-duplex link up to four miles apart. It is the 4-wire, RS-232 Short-Haul Modem‑C Async variant and uses a DB9 RS‑232 interface on the modem side, with 24 external mini DIP switches to support a wide range of line rates, parity, and handshaking options. Front-panel indicators consist of two dual LED groups (red/green) that show transmit/receive status and verify twisted-pair polarity, helping installers diagnose wiring and operation quickly. The ME800A‑R4 is offered as a standalone unit or in SHM‑B Async rackmount form, is TA A compliant, and is commonly deployed in point‑of‑sale, industrial, and security applications where extending serial interfaces over CATx cables is advantageous for connecting serial devices across longer copper runs.