6
The MiniPlex-2 Multiplexer
The MiniPlex-2 multiplexer is an advanced NMEA 0183 multiplexer with four NMEA inputs or listener
ports, two NMEA outputs or talker ports and one or two host interfaces.
It combines NMEA sentences that are received on the NMEA
inputs and it can send these sentences to the NMEA outputs
and to the host interface(s). These host interfaces can also
be used to send NMEA sentences back to the multiplexer to
be forwarded to its NMEA outputs and to send commands to
configure the multiplexer.
Figure 4 shows a typical setup where the MiniPlex-2 is used
to combine data from four instruments, send it to a PC and,
depending on the configuration of the MiniPlex, send the
same data to an autopilot and a repeater display. The PC is
also capable of controlling the autopilot to steer a
programmed route and to display information such as
distance to next waypoint on the repeater display.
Galvanic Isolation
Every NMEA input of the MiniPlex-2 is galvanically isolated,
sometimes called opto-isolation because opto-couplers are used to achieve this isolation. An opto-coupler
is an electronic component that transports information by means of light instead of electricity, thus
creating a barrier for electrical currents and voltages.
A galvanically isolated input prevents unwanted flow of electrical currents between instruments and the
multiplexer. These currents could damage the instruments or interfere with radio signals and should
therefore be avoided. Galvanically isolated inputs are required by the NMEA 0183 standard.
The host port or interface of the MiniPlex is also galvanically isolated in order to isolate the host from the
navigation network and protect it against potential damage caused by ground loops or voltage spikes.
Outputs
Both NMEA outputs can drive up to four listeners each. Flexible routing options allow you to specify which
NMEA sentences are sent to these outputs. The outputs are not galvanically isolated. The NMEA 0183
standard does not require this. It isn’t necessary either, because each connected input is galvanically
isolated.
Feature Set
Besides the basic functionality of combining NMEA sentences from multiple sources, the MiniPlex-2 offers
a range of features like sentence filtering and routing, input priority with automatic switchover, testing of
data integrity, NMEA conversions, Talker ID modification and SeaTalk
®
to NMEA translation.
The MiniPlex-2 can be integrated seamlessly into an existing Raymarine SeaTalk network when SeaTalk
mode is enabled. This mode changes one NMEA input into a SeaTalk input. When connected to a
Raymarine SeaTalk network, the multiplexer translates SeaTalk data into NMEA sentences and combines
these with NMEA sentences that are received on the other inputs. Only one SeaTalk input is needed since
the SeaTalk bus connects all instruments together through one single cable.
SeaTalk to NMEA translation in the MiniPlex works one-way only: no NMEA sentences are converted into
SeaTalk, the multiplexer just listens on the SeaTalk bus.
All MiniPlex-2 models have the same features and number of NMEA inputs and outputs. The only
difference between each model is the type of host port. The following chapters describe the details of
each host port.
Figure 4
PC
GPS
Depth
Wind
Log
MiniPlex-2
In1
In2
In3
In4
Out1
Out2
Host
Autopilot
Repeater
