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yslogotypeTAG.gif (2871 bytes) · Electronics Interfacing ·

Combining Multiple NMEA Sources
Going to One Device

· NoLand NMEA NM42 0183 Serial Multiplexer
Improved Model NM42 for 2003 · ysprice.gif (1089 bytes)$210

nolandsm.jpg (10375 bytes)If you need to connect multiple NMEA sources
to your computer or instrument system,
but only have one port to receive all the data,
this multiplexer will solve the problem for you!

nolanddiagsm.jpg (15155 bytes)The NoLand NM42 is the updated and improved version of the industry standard N183-41 serial multiplexer.  It combines up to four NMEA instruments into a single RS-232C output for use by a computer, instrument system, or other NMEA listener. The multiplexer reads and stores the incoming data from each instrument.   Whenever a complete message is received, the multiplexer automatically dumps it to the RS-232C output, even while it is still reading the inputs. Therefore, complete messages are dumped as soon as they are received without any loss of input data. A "Talker" port is also included to allow the computer to request specific messages from instruments or to send data such as waypoints or steering commands.

Installation of multiplexer is quite simple. The module may be mounted to any convenient surface with all connections made via a terminal strip. A DB9 9-pin connector is provided for PC connection if desired.  The unit is fully automatic in that once power is applied, it immediately begins acquiring data without user interaction. No software drivers or software configuration are needed.  

An LED shows operating status of the multiplexer.  Green indicates an input is receiving valid data.  Red indicates the talker port (TLK) is sending data.  Yellow-orange indicates an error has occurred.  Error messages are sent to the outputs to aid in fault detection.,

If more than four inputs are needed, multiple modules may be ganged together.



  • 4 NMEA 0183 Inputs
  • NMEA 0183 Talker Port (RS-422)
  • 1 RS-422 Output
  • 1 Full Duplex RS-232 Port
  • Selectable Output Baud, 4800/9600
  • Multicolor status LED




Supply Voltage: 8-20 Vdc
Supply Current (@12 Vdc): 50 ma (tyical).
Input drive Voltage (min/max): 0.5/14V (active state)
Input impedance: 12K ohms (min).
Talker output level: 5V Differential per RS-422
Serial output data rate: 4800, 9600 baud (selectable)
Serial output format: RS-232C or NMEA 0183/RS-422
Size: 4.4 x 3.65 x 1.0 inches
Weight: 4 oz.
Warranty: 2 year replacement


yachtSOFT.com, LLC · tel: 1(800)483-8100, code #97 (outside NY Metro) or 1(516)482-8800 ·  fax: 1(516)482-8801 ·
· web: http://www.yachtsoft.com · e-mail: multiplexer@yachtsoft.com ·

yachtSOFT.comtm can bundle complete packages for you, including marinized laptop computers, pre-installed software including electronic charting and CD-ROM charts, weatherfax, yacht management, along with hand-held GPS, etc., making the transition to marine computing as easy as possible. Please contact us to assemble a system that works for you, and within your budget.



or call:

1(800)483-8100, code #97
(outide NY Metro), or


Please e-mail or telephone us if you have any questions about or would like to order
a NMEA Multiplexer, or any other hardware, software or equipment.


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