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MiniPlex3-USB MODBUS to NMEA Converter and Multiplexer

MiniPlex3-USB MODBUS to NMEA Converter and Multiplexer

Quick Overview

MiniPlex-3-USB NMEA multiplexer with 4 NMEA inputs or MODBUS inputs and 2NMEA outputs and USB PC interface
View Options


The MiniPlex-3-USB can combine the data from up to 4 NMEA0183 devices or MODBUS devices, and send the data to two programmable NMEA0183 outputs and 1 USB output to a PC

Compatible with NMEA0183, MODBUS, and Raymarine SeaTalk data.

The MiniPlex-3-USB combines data from up to 4 NMEA 0183 or MODBUS inputs ( one of which can be SeaTalk) and outputs the data to two NMEA0183 outputs and 1 PC USB output.

All data is available on one or more computer interfaces in NMEA 0183 format.

Each and every port on a MiniPlex-3 multiplexer is galvanically isolated from the internal electronics and from every other port. This guarantees that no ground loops will be created when adding a MiniPlex-3 to a navigation network. It also ensures a trouble free connection to any type of NMEA 0183 port of any device.


The MiniPlex-3 Series has a rich set of features and configuration options, enabling the user to tackle almost any NMEA bottleneck or interface problem. The configuration tool MPX-Config3 allows full configuration of the multiplexer and monitoring of NMEA data passing through the multiplexer.

NMEA routing
NMEA or MODBUS data can be routed from any input to any output. A default route can be set as well as specific routing rules for individual NMEA sentences. Computer data can be routed to any NMEA output, to be merged with other NMEA data or to override this data. This enables automatic switching between computer based navigation and GPS/instrument based navigation.

NMEA filtering
A flexible NMEA filter can be configured to pass or block specific sentences from each input channel. This greatly reduces the chance of an overflow and the resulting loss of data. Many GPS receivers for instance, transmit an abundance of sentences every second, accounting for 85% of the available bandwidth of an NMEA 0183 port at 4800 Baud. By blocking unwanted or unnecessary sentences, bandwidth is preserved for other instruments. The filter can also be configured to reduce the rate of specific NMEA sentences.

Flexible communication speed

The communication speed of all inputs and outputs can be set from 4800 to 57600 Baud to allow connection of devices that operate at non-standard (4800 Baud) communication speeds like integrated weather sensors, gyro compasses or AIS receivers and transponders.

SeaTalk® conversion
When Input 1 is set to SeaTalk mode, this NMEA input becomes a bi-directional SeaTalk port, offering conversion between the most common SeaTalk datagrams on a Raymarine SeaTalk1® network and their NMEA 0183 counterparts. These sentences are combined with NMEA sentences received on the other inputs. When Priority is enabled, SeaTalk data can be assigned highest or lowest priority. Currently, only conversion from SeaTalk1 to NMEA 0183 supported. Conversion from NMEA 0183 to SeaTalk1 will be available soon through a firmware update.

With Priority enabled, similar NMEA sentences on different inputs are only passed from the input with the highest priority. When for instance two GPS receivers are connected to inputs 1 and 2, and both transmit the same type of NMEA sentences, only those received on input 1 are passed. An adjustable time-out ensures that similar sentences from the GPS at input 2 are passed when the GPS at input 1 stops sending these sentences. Optionally, GPS sentences are checked for a valid status field, causing automatic switchover when the primary GPS looses satellite signal. An additional option to check the GPS status flags can be enabled to ensure that data received from a GPS which lost satellite reception is also blocked.

Channel information
This features adds an extra $MXSTN sentence or a TAG block to NMEA sentences to indicate on which NMEA input a sentence is received.

Talker ID substitution
Talker ID substitution changes the talker ID of incoming sentences. The talker ID can be specified for each input channel. This option is useful for software or instruments that expect a specific talker ID or to distinguish between sentences from two similar instruments.

NMEA conversions

The MiniPlex-3 offers several conversion options for NMEA sentences:

  • Magnetic to True heading conversion and vice versa
  • GPS speed to Log speed and vice versa
  • Reverse True heading
  • Old (VWR) to new (MWV) wind sentences and vice versa
  • Relative/Apparent to Theoretical/True wind
  • RMC to GGA
mpx config
MiniPlex-3USB Technical specifications:

Supply voltage:

8-35vDC, secured against reversed polarity.

Current consumption:

50mA (100mA max. with fully loaded talker ports).

Computer interface:

USB, galvanically isolated.


4 x NMEA 0183/RS-422 or MODBUS galvanically isolated.
Input 1 can be set to SeaTalk mode.

Input resistance:

> 1.4 kOhm

Input current:

0.5mA @ 2V
3.0mA @ 5V
7.1mA @ 10V


2 x NMEA 0183/RS-422, galvanically isolated.

Max ouput current:

20mA @ > 2V

Filter list size:

50 sentence types

Priority list size:

50 sentence types

Speed NMEA In 1-3:

4800 - 57600 baud

Speed NMEA In 4/Out 1:

4800 - 57600 baud

Speed NMEA Out 2:

4800 - 115200 baud


138 x 62 x 30mm

Availability: Stock Item


Components / Downloads

For further information, technical advice, or a quotation please call or email us. If you are not sure which product you need one of our technical sales advisors will be happy to discuss your application. We also accept company purchase orders by fax or post. Credit card orders can also be placed over the phone for any product.

MiniPlex Protocol Converter
MiniPlex-3-USB Modbus to NMEA0183 Protocol Converter. 4 x RS422 Input (NMEA or MODBUS) and 2 x RS422 Modbus NMEA outputs. USB PC connection for programming and NMEA data output.
or call us for a quote