Yacht Devices NMEA 0183 User manual

User Manual
NMEA 0183 Multiplexer YDNM-02
Firmware version
1.00
2019

© 2019 Yacht Devices Ltd. Document YDNM02-001. March 13, 2019. Web: http://www.yachtd.com/
NMEA 2000® is a registered trademark of the National Marine Electronics Association. SeaTalk NG
is a registered trademark of Raymarine UK Limited. Garmin® is a registered trademark of Garmin Ltd.

Contents
Introduction 4
Warranty and Technical Support 5
I. Product Specication 6
II. NMEA 0183 Basics 8
III. Installation and Connection of Device 10
IV. LED Signals 13
V. Selecting Presets and Settings Reset 15
VI. Routing and Data Filters 16
VII. Device Conguration with NMEA 0183 Commands 19
VIII. Firmware Update 27
APPENDIX А. Troubleshooting 29
APPENDIX B. Conguration Presets 31
APPENDIX C. Conversions Between SeaTalk and NMEA 0183 37
Package Contents
Device 1 pc.
This Manual 1 pc.
Screws 2 pcs.
Paperclip for reset 1 pc.

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Introduction
The NMEA 0183 Multiplexer (hereinafter Multiplexer or Device) is a congurable NMEA 0183 and SeaTalk
multiplexer. The Multiplexer has six conguration presets with different port speeds and routing schemes.
Presets can be selected by pressing the Device’s hidden button (a paper clip is required, supplied with
the Device). This makes installation very easy: select a suitable preset from Appendix B and set it up with
a few clicks!
The Multiplexer has ve physical NMEA 0183 ports (ve inputs and three outputs) with congurable
speed from 300 to 115200 baud. This allows organization of data exchange between multiple devices
with different speeds. Multiple physical listeners can be connected to the Multiplexer’s outputs. Port #4
is galvanically isolated and has ve terminals: four data terminals (TX+, TX-, RX+, RX-) and a dedicated
ground (also isolated from other ports and Multiplexer’s ground).
The Device is supplied with preset #1 activated (its settings are printed on the Device’s case). In this preset
three of the ve NMEA 0183 ports are congured for automatic port speed detection. This means that
in most cases you need not worry about the speed of the NMEA 0183 equipment that you connect. Port #2
is congured to lter out outgoing AIS messages, to prevent occasional ooding of this port congured for
4800 baud speed.
SeaTalk is a proprietary binary protocol of Raymarine company. It allows co-existence of multiple devices
on the bus, so the Multiplexer has only one SeaTalk port. A bi-directional converter between SeaTalk and
NMEA 0183 supports all known SeaTalk datagrams, including autopilot (see Appendix C for details). This
allows controlling SeaTalk autopilots from NMEA 0183 chart plotters and marine apps.
To change settings of conguration presets or update Multiplexer’s rmware, you need a laptop or PC
with either a serial (COM) port or USB-to-COM adaptor. You can congure physical ports speed, set up
routing between ports and dene data lters to reduce trafc on low-speed ports with special NMEA 0183
commands described at sections VI and VII.
Thank you for purchasing our product and happy voyages!

— 5 —
Warranty and Technical Support
1. The Device warranty is valid for two years from the date of purchase. If the Device was purchased
in a retail store, the sales receipt may be requested when applying for a warranty claim.
2. The Device warranty is terminated in case of violation of the instructions in this Manual, case
integrity breach, or repair or modication of the Device without the manufacturer’s written
permission.
3. If a warranty request is accepted, the defective Device must be sent to the manufacturer.
4. The warranty liabilities include repair and/or replacement of the goods and do not include the cost
of equipment installation and conguration, or shipping of the defective Device to the manufacturer.
5. Responsibility of the manufacturer in case of any damage as a consequence of the Device’s operation
or installation is limited to the Device cost.
6. The manufacturer is not responsible for any errors and inaccuracies in guides and instructions
of other companies.
7. The Device requires no maintenance. The Device’s case is non-dismountable.
8. In the event of a failure, please refer to Appendix A before contacting technical support.
9. The manufacturer accepts applications under warranty and provides technical support only
via e-mail or through authorized dealers.
10. The contact details of the manufacturer and a list of the authorized dealers are published
on the website: http://www.yachtd.com/.

— 6 —
I. Product Specification
Figure 1. Drawing of Multiplexer

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Device parameter Value Unit
Supply voltage 7..16 V
Current consumption, maximum, all ports with 100 Ohm load 60 mA
NMEA 0183 ports (inputs / outputs) 5 / 3 —
SeaTalk 1 ports 1 —
Receiver input resistance (port #1, #2, #3, #5 / port #4) 12 / 96 kOhm
Galvanic isolation of NMEA 0183 port #4 2500 V
RMS
Device case dimensions (LxWxH) 85x45x28 mm
Weight 80 g
Operating temperature range -20..55 °С
Yacht Devices Ltd declares that this product is compliant with the essential requirements of EMC
directive 2004/108/EC.
Dispose of this product in accordance with the WEEE Directive. Do not mix electronic disposal
with domestic or industrial refuse.

— 8 —
II. NMEA 0183 Basics
The default speed of a NMEA 0183 interface is 4800 baud. High-speed interfaces are 38400 baud and were
designed especially for AIS, but usually chart plotters and instrument displays allow any data (not only AIS)
on a high-speed port. On a chart plotter, port speed can be congured in the settings. NMEA 0183 uses
different wires for talking (transmitting, TX) and listening (receiving, RX) data.
One talker can be connected to multiple listeners, but a listener can have only one talker connected.
The Device can act as a «multiplexer» and join the output of multiple physical talkers to a single data
stream.
Figure 1. (a) RS-232 and (b) RS-422
NMEA 0183, until version 2.0 (1992), used a «single ended» RS-232 interface with one TX line and one
RX signal line (grey at Figure 1.a) and ground line (dotted at Figure 1.a) used as reference for TX and RX
signals. Therefore, old devices have only three wires.
Since Version 2.0, NMEA 0183 has been based on a «differential» RS-422 interface, which has two RX lines
RX+ (can also be marked as «A») and RX- (or «B»), two TX lines TX+ (or «A», grey at Figure 1.b) and TX-
(or «B», dotted at Figure 1) and a ground (not shown at Figure 1.b). Modern devices use ve wires.

— 9 —
Devices of different versions can be connected, but with one cautionary note. TX- («B») is not equal to a
ground line. Voltage on the TX- line (dotted on Figure 1.b) changes from 0 to 5V, and connecting this line
to ground line can cause a short circuit.
The correct connection schemes are shown in Figure 2.
Figure 2. Connection of NMEA 0183 devices

— 10 —
III. Installation and Connection of Device
The Device requires no maintenance. When deciding where to install the Device, choose a dry mounting
location. Despite the fact that the Multiplexer case is waterproof, the terminals are open and seawater
can cause a short circuit. Do not place the Device where it can be ooded by water, get wet in the rain
or be sprayed with water.
Figure 1. Multiplexer wire terminals (left) and LED’s scheme (right)
The Multiplexer can be xed horizontally or vertically using the two screw holes (4 mm diameter, 72 mm
between centers) and the screws supplied. When the holes of wire terminals are pointing to the sides, they
are better protected from occasional water spray.

— 11 —
The Multiplexer requires a DC power source from +7 to +16 V, which should be connected to its
VCC (positive) and GND (negative) terminals (see Figure 1). It can be also powered from a SeaTalk bus
(see below).
All connections should be made when the power is off. This will protect against accidental short circuits
during installation. When the power and ground wires are connected, turn on the power supply and
the Device’s LEDs will blink (see the next Section).
1. NMEA 0183 equipment connection
The connection to the NMEA 0183 network varies depending on the version of the connecting
equipment. Please, refer to Section II for connection schemas. The wrong wiring can damage
the equipment!
The Multiplexer is supplied with ve NMEA 0183 ports: two bidirectional (#1 and #2), one bidirectional
and fully galvanically isolated (#4), and two input-only ports (#3 and #5). By pressing a hidden button
on the Device you can select one of 6 user-congurable presets with different port speeds and data
routing settings. In factory conguration, preset #1 is activated (refer to Appendix B), its factory settings
are printed on the Devices’ case.
Please note that bi-directional port #1 is congured for automatic speed detection. This means,
that until data is received from this port, the Device will not send data to it, because the port speed
is unknown. Detections starts from 4800 bps speed, and in the worst case the rst sentence from the port
will not be received correctly.
The only known type of equipment which may not work well with automatic speed detection is VHF DSC,
which sends only messages about DSC calls and needs in GPS position, it is unknown when VHF DSC sends
its rst message.
The ground wire of high-speed ports (38400 bps) should be connected to the Multiplexer’s ground
terminal. In case of connection to isolated port #4, the ground wire of the equipment should be connected
to the dedicated ground terminal of port #4 («GND4» at Figure 1).

— 12 —
2. SeaTalk bus connection
A SeaTalk bus has three wires: 12-Volt power supply (red label on equipment, red lead within a SeaTalk
cable), ground (white or grey label on equipment, bare shield within a SeaTalk cable) and data (yellow label,
yellow lead within a cable).
The Multiplexer can also be powered from the SeaTalk bus: ground and power supply wires of the SeaTalk
bus should be connected to the Multiplexer’s VCC and Ground terminals on the left side (see Figure
1), the data wire should be connected to the «SeaTalk» terminal on the Multiplexer’s left side. In case
of powering of the Multiplexer from another source, the ground wire of the SeaTalk bus should be connected
to the Multiplexer’s ground terminal (GND) on the left side.

— 13 —
IV. LED Signals
The Device is equipped with six bi-color port LEDs (SeaTalk port and NMEA ports #1–#5 — see the Figure
1 in the previous Section).
1. Signals during the power-on or preset change
At power-on or upon the preset change all LEDs light up for a few seconds depending on the congured
port speeds: the corresponding port LED will be green if the port speed is set to 4800, red otherwise.
The SeaTalk port speed is always set to 4800 baud and the corresponding port LED should be green.
Next, the single red LED lights up, indicating the current preset number (ports #1–#5 LEDs correspond
to presets #1–#5, SeaTalk port — to preset #6).
Then all LEDs light up for a few seconds again, depending on the congured port speeds: the corresponding
port LED will be green if the port speed is set to 38400, red otherwise. SeaTalk port LED should be red.
Ports congured for automatic speed detection will blink RED in both cases.
After this sequence the LEDs start ashing in normal operation mode.
2. Signals during normal operation
During normal operation, the Device produces a series of four ashes of each port LED every ten seconds
(counter-clockwise in direction, in the following order: port #1, #2, #3, #4, #5, SeaTalk). The ashes indicate
the state of the Device interfaces over the last ten seconds and have the following meaning:
• Port LED, ash #1: data received. Green, if any data was received by this port in the last 10
seconds (even if they were ltered out later, see the Section VI).
• Port LED, ash #2: RX errors. Green, if any data was received and all data was received without
errors. NMEA 0183 sentences contain a checksum, so any transmission error will be detected.

— 14 —
• Port LED, ash #3: data sent. Green, if data was sent from this port. As there is no conrmation
of reception, this signal does not mean that data was received by any listener. Red means that
the Multiplexer has nothing to send.
• Port LED, ash #4: TX overow. Green, if data was sent without overow. In case of a red
signal, you should increase the port speed (if possible) or lter out unnecessary data, because
the selected speed is not enough to send all the data. This signal will also be red if ash #3 is red.
3. Signals during device reset
LED signals during device reset are described in Section V.
4. Signals during rmware update
LED signals during rmware update procedure are described in Section VIII.

— 15 —
V. Selecting Presets and Settings Reset
1. Selecting a preset
The Multiplexer has 6 user-congurable presets with different routing schemes and port speeds
(see Appendix B). Insert the paper clip into the small hole near the SeaTalk LEDs (see the button location
at Figure 1 in Section III) and briey press it to activate the next preset. Port speeds and current preset
number will be indicated by Multiplexer’s LEDs according to Section IV.1.
Any preset can be later modied with conguration commands (see Section VII.1). To return to the default
factory settings, perform a settings reset.
It is also possible to disable/enable the preset selection function of a button using a conguration
commands (see Section VII.4). If the preset selection function is disabled, the Device’s button can only
reset the Device’s settings to a factory default.
2. Settings reset
To reset the device to a factory conguration, press and hold the hidden button. Port #1’s LED will shine
red. Wait 10 seconds and the port #1 LED will change from red to green. Release the button while the LED
is green to reset the Device’s settings. Reset is conrmed by the Device with a power-on LED sequence with
active routing preset #1 (see Section IV.1). If you keep pressing the button, the LED will become red 2-3
seconds later. If you release the button while the LED is red, device will not perform a reset.

— 16 —
VI. Routing and Data Filters
1. Routing
Figure 1. In-line connection
Different devices can be connected to the input and output wires of the same port of the Multiplexer. In
this case you may need to specify that this port is the output for itself (available in presets #4 and #6). This
also allows connecting the Multiplexer «in-line»with two devices (see Figure 1) to enrich the data stream
with data from other ports.
The Multiplexer ignores incorrect received sentences, including sentences with an invalid checksum.
The “Tunnel” port setting allows routing of incorrect sentences from this port. It allows connecting Navtex

— 17 —
and rare NMEA equipment produced decades ago when a checksum was not a mandatory part of the
sentence.
Invalid sentences are not processed by incoming lters or outgoing lters. Correct sentences are always
processed by lters, whether tunneling is off or on.
2. Data lters
The Device has 20 lters, which allow limiting the set of incoming or outgoing sentences on each port. Each
port has four lter lists: two for incoming NMEA 0183 sentences (one for sentence formatters and one
for the talker ID), and two the same for outgoing sentences (except for ports #3 and #5 which have no
physical outputs).
The lter set is global, meaning that it is not tied to a preset. If you change the active preset the lters will
not be changed.
Each lter list has a switchable type: WHITE or BLACK. A message is passed through the WHITE lter if
it contains a record matched with a message. And the reverse for BLACK. In the factory settings, all lter
lists (with one exception) are empty and are of BLACK type, so all messages are passed through the lters.
According to the standard, an NMEA 0183 sentence starts with a $ or ! symbol, followed by a two-character
talker ID and a 3-char sentence formatter. These elements are followed by data elds (after the comma).
The sentence is nished by a checksum after the * (asterisk) symbol.
The following sentences matches to GLL and VDM records in the sentence lter or GP and AI records
in the talker ID lter:
$GPGLL,4146.5894,N,07029.6952,W,173412.02,A*15
!AIVDM,1,1,,B,ENk`smq71h@@@@@@@@@@@@@@@@@=MeR6<7rpP00003vf400,4*5F
The Talker ID lter contains 2-char talker IDs separated by a space character, and sentence lters contain
The only exception is port #2 which lters out outgoing AIS messages (VDO and VDM)
to prevent ooding of low speed equipment connected to this port.

— 18 —
3-char NMEA 0183 sentence formatters separated by a comma character. Example of sentences and talker
IDs lters:
• GLL,VDM,VDO
• GP,AI
Filters allow reduction of the port load. If the fourth ash of the port’s LED indicates overow (see Section
IV.2), unnecessary messages can be excluded using the transmit lter of this port.
The Multiplexer has a bi-directional converter between SeaTalk and NMEA 0183. On the Seatalk port you
can use NMEA 0183 lters and datagram lters («Sxx», where xx is a hexadecimal datagram number, see
Appendix C). For example, NMEA 0183 water temperature MTW sentence is converted to Seatalk datagrams
23 and 27 (hexadecimal). To prevent sending water temperature to or from SeaTalk, you can specify the
sentence lter «MTW» (temperature will be ltered out at NMEA 0183 level) or «S23 S27» (will be ltered
at datagram level).
In case of a WHITE lter on the SeaTalk port, you should specify «MTW S23 S27»to allow water
temperature processing because you need allow processing of SeaTalk datagrams 23 and 27 and generation
of MTW sentence.
Conguration procedures for setting the routing scheme and data lters are given in the next Section.

— 19 —
VII. Device Configuration with NMEA 0183 Commands
If none of the factory routing schemes and baud rate presets (given in Appendix B) satises your equipment
requirements or you need to set up data ltering (see VI), you will need to congure the Multiplexer
by sending a special NMEA 0183 sentences to any port from #1 to #5. The Multiplexer will reply
to the commands on the same port they were received, thus you cannot get a reply on ports #3 and #5
as they are input-only.
Connect the Multiplexer to a serial port of a PC either directly or with a COM-to-USB adaptor. You will need
an RS-232 or RS-485/RS-422 compatible COM-to-USB adaptor.
Connect hardware serial ports or RS-232 COM-to-USB adaptor only to the isolated port #4
to avoid possible different ground potential issues.
Use a COM-port terminal application like putty (free download at www.putty.org) to enter
and send the NMEA 0183 conguration commands. Congure the COM-port baud rate in a terminal
application to match the current port baud rate setting, set the number of data bits to 8, number of stop
bits 1, disable parity check. If you have sent the command to change the port baud rate to the Multiplexer,
you should reconnect the terminal application using a new port baud rate.
When using a terminal application which sends data immediately upon enter, it is recommended to type
the command rst in a text editor and then copy the whole string to a terminal.
Note that conguration commands $YDMPX are always received by Device and cannot be blocked by lters
or other settings.
Conguration commands do not require a correct NMEA 0183 checksum, two zero characters
(00) can be used. However, if you send commands through other NMEA 0183 equipment like
a third-party multiplexer, you will need to enter a valid checksum. You can use, for example,
an online NMEA 0183 checksum calculator.

— 20 —
1. Port speed and routing scheme setting commands
$YDMPX,p,BPS,b*cc
p — port number 1..5;
b — baud rate;
cc – valid NMEA 0183 checksum or 00.
The BPS command sets the baud rate for specied port. Supported baud rates are 300, 1200, 2400, 4800,
9600, 19200, 38400, 57600, 115200 or AUTO. With AUTO setting, the port baud rate will be automatically
determined by the Device upon valid NMEA 0183 data reception. Supported baud rates for AUTO mode
are 4800, 9600 and 38400. In AUTO mode, the Device will not output data on the corresponding output
port with until the baud rate is determined.
Example 1: $YDMPX,5,BPS,38400*3F — set the port #5 baud rate to 38400 baud.
Example 2: $YDMPX,1,BPS,AUTO*0B — set the port #1 baud rate to be automatically determined
by Device.
$YDMPX,p,RTE,f,out1[,out2[,...]*cc
p — input port number 1..5 or S for SeaTalk port.
f — tunneling ag, T = tunneling is enabled, empty eld if disabled;
outN — comma separated list of output ports, numbers 1 - 5 or S for SeaTalk port;
cc – valid NMEA 0183 checksum or 00.
The RTE command sets the routing scheme from an input port to multiple output ports for the current
preset and modies the tunneling setting for input port.
Example 1: $YDMPX,4,RTE,T,1,2,5*4D — forward port #4 input data to ports #1,#2 and #5 and enable
tunneling of messages, received on port #4.
Example 2: $YDMPX,4,RTE,,1,2,5*19 — forward port #4 input data to ports #1,#2 and #5 and disable
tunneling of messages, received on port #4.