Data Multiplier Buffer and Splitter
NM-251A
Power Supply
12 or 24 VDC
Input Ports
2 x isolated NMEA0183®
Output Ports
4 x buffered RS422/TTL (general purpose) + 1 x RS232 (bidirectional I/O)
The NM-251A is a robust NMEA0183® data multiplier, buffer, and splitter, specifically designed for systems requiring reliable signal distribution and source management. Featuring two optically isolated inputs to five buffered outputs (four RS422/TTL and one RS232), it efficiently multiplies data from one or two NMEA0183® sources, with an integrated priority encoding function (fallback mode) to ensure continuous data flow from the most significant input. The unit includes two optically isolated inputs as well as a bidirectional RS232 port that acts as both a talker and listener, allowing data exchange with a PC charting system or other listeners. It is an ideal, high-quality solution for safely distributing navigational data from one or two sources to multiple listeners on a vessel, ensuring data integrity and providing failsafe functionality across complex serial communication setups
Specifications
| Power Supply | 12 or 24 VDC |
| Input Ports | 2 x isolated NMEA0183® |
| Speed/Baud Rate | 4800 to 38400 bps |
| Output Ports | 4 x buffered RS422/TTL (general purpose) + 1 x RS232 (bidirectional I/O) |
Features & Functions
- 2 inputs optically isolated NMEA0183®
- 5 outputs channels (4 x RS422/TTL + 1 x Bi-directional RS232)
- Optical isolation on inputs for power protection
- 3 selectable modes:
- Fallback Mode — auto-switches to backup input (Watchdog)
- Mux Mode — combines both inputs to all outputs
- Split/Mux Mode — splits inputs to separate output pairs
- User-selectable output baud rate (up to 38400 bps)
- Dedicated RS232 port for PC/Talker use
- IEC 60945 certified (marine standard)