Overview
The Black Box ME800A-E is an asynchronous short-haul modem designed to extend RS-232 serial device communications up to 4 miles (6.4 km) over standard twisted-pair cabling. This 4-wire line driver and receiver pair eliminates the cost and complexity of dedicated telecommunications lines for industrial applications, offices, and data centers. The ME800A-E operates as a full-duplex EIA-232/CCITT V.24 interface, supporting data rates up to 115.2 kbps.
Key Features
- 4-wire asynchronous full-duplex design extends RS-232 communications to 4 miles
- Data rates up to 115.2 kbps at short distances; 9600 bps at 4-mile maximum distance
- Switch-selectable DCE/DTE configuration eliminates special cable requirements
- EIA-232 hardware handshake control with status monitoring LEDs
- Built-in loopback switch for testing and troubleshooting
- Operates over 24–26 AWG unshielded twisted-pair telephone cable
Technical Specifications
- Maximum Distance: 4 miles (6.4 km)
- Data Rate (Max): 115.2 kbps at 4000 feet; 57.6 kbps at 1 mile; 9600 bps at 4 miles
- Interface: EIA-232/CCITT V.24, asynchronous full-duplex
- Configuration: Switch-selectable DTE/DCE
- Connectors: DB25 and/or 4-screw terminal block; RJ-11 jack for twisted-pair
- Control Lines: EIA-232 hardware handshake (RTS, CTS, DTR, DSR, DCD)
- Data Flow Control: X-ON/X-OFF software handshake
- Cabling: 24–26 AWG unshielded twisted-pair (0.083 pf/mile capacitance)
- Enclosure: High-impact plastic standalone unit
- Power: 230 VAC ±10%, 50–60 Hz (transformer supplied)
- Status Indicators: LED monitors for TD (transmit) and RD (receive) data
- Certifications: FCC Class A, UL, CSA approved
Typical Applications
The Black Box ME800A-E is ideal for:
- Industrial process control and SCADA systems requiring extended RS-232 reach
- Connecting legacy serial devices (DEC, HP, UNIX systems) across facility distances
- Security system data transmission over in-house twisted-pair wiring
- Point-to-point asynchronous communications in factories, warehouses, and remote sites
- Extending printer, terminal, and modem connections beyond standard 50-foot RS-232 limitations
- Data center and telecommunications environments where serial device extension is required
Compatibility & Replacements
Compatible With
- Any RS-232 DCE or DTE serial device (computers, terminals, printers, modems, PLCs)
- EIA-232 and CCITT V.24 serial interfaces
- Point-to-point 4-wire twisted-pair transmission networks
- Industrial automation controllers and SCADA systems
- Legacy equipment using standard serial communication protocols
Replaces / Drop-In Replacement For
- Black Box ME800A (standard 115 VAC model)
- Black Box ME800A-R2 and ME800A-R3 (includes cable versions)
- Black Box ME805-C (rackmount card variant)
- Most Black Box SHM-B Async short-haul modem models from the same generation
Works With
- Standard EIA-232 serial interfaces and protocols
- X-ON/X-OFF software flow control
- RTS/CTS and DTR/DSR hardware handshake protocols
- Asynchronous data transmission (no clock signal required)
- 4-wire twisted-pair and dedicated telephone-grade cabling
- Full-duplex bidirectional communication networks
