4
Introduction
The MiniPlex-2 series NMEA multiplexers enable the connection of multiple NMEA 0183 devices and a host
device like a PC, a laptop or a tablet. All models share the same number of NMEA ports and features.
They differ in the type of host interface, the interface that talks to the computer.
This manual covers all models of the MiniPlex-2 series. There is a chapter for each type of host port. The
remaining part of the manual covers NMEA connections and configuration, which are the same for all
models.
We will also explain NMEA 0183 and how things connect (or not).
NMEA 0183
The NMEA 0183 Standard, a communication standard defined by the NMEA organization
(www.nmea.org), defines a communication protocol called NMEA 0183 that enables navigation
instruments and devices to exchange data with each other.
This way, a compass can send a heading to a radar to enable a north-up display, a GPS can send cross-
track and waypoint information to an autopilot in order to steer a programmed course.
NMEA Sentences
NMEA data is made up of readable text sentences. If you would connect the output of a navigation
instrument to the serial port of a computer and start a program that displays the incoming data, you
would see something like this:
$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*2E
$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*39
$GPGLL,5301.0061,N,00635.5479,E,143357.999,A*22
$HEHDT,67.0,T*1E
This is plain text in a format that is laid out in the NMEA 0183 standard. Every device that receives this
information would know that the sentence starting with GPGLL originates from a GPS (hence the GP at
the beginning of the sentence) and that it contains the geographic longitude and latitude (GLL).
The term “NMEA sentence” is used for NMEA data because it is made up of single lines of text.
Throughout this manual, “NMEA sentences” and “NMEA data” will be used randomly.
Talkers and Listeners
The NMEA 0183 standard defines talkers and listeners. A device that sends information is a talker and a
device that receives information is a listener. When connected to each other, the talker sends information
to the listener.
Communication using the NMEA 0183 protocol involves at least one talker
sending data to one listener. Figure 1 on the right shows such a minimal
system: a gyrocompass sends heading data to a radar.
It is important to know that a talker or listener port is named after its
function, not after what it is connected to. So a talker port sends out
information but it connects to a listener. This might be confusing at times so further in this manual we
will use the terms input and output instead of listener and talker port respectively.
The NMEA 0183 standard specifies that a talker should have enough driving capacity to talk to four
listeners. This is as easy to achieve as telling a story to an audience of four people - the only requirement
is to talk loud enough.
Gyro
Radar
Figure 1
