Raymarine NMEA Multiplexer User Manual

NMEA Multiplexer

Owner’s Handbook

Document Numb er: 81250-1

Date: February 2005

© Copyright Rayma rine (UK) Ltd 2005

Preface

Congratulati ons on having bought a Ra ymarine NMEA
Multiplexer. This enables you to combi ne NMEA outputs from up
to four devices, to provide a combined output to four other
devices.

CAUTION: Electrical safety

Make sure you have switched off the power supply
before you start installing this product.

Important inform ation

To the best of our knowledge, the information in this handbook was correct
when it went to pr ess. However, Raymarine cannot accept liability for any
inaccuracies or omissions it may contain.

In addition, ou r policy of continuo us product improve ment may change
specificati ons without notic e. Therefore, Raymarine cannot accept liability
for any differences between the product and this guide.

EMC Installation Guidelines

All Raymarine equipment and accessories are designed to the best industry
standards for use in the recrea tional marine environment.

Their design and manufacture conforms to the appropriate Electromagnetic
Compatibilit y (EMC) standar ds, but correct in stallation is r equired to ens ure
that performance is not compromised. Although every effort has been taken
to ensure that they will perform under all conditions, it is important to
understand w hat factors could aff ect the operation o f the product.

The guidelines given here describe the conditions for optimum EMC
performance, but it is recognized that it may not be possible to meet all of
these conditions in all situations. To ensure the best possible conditions for
EMC performance with in the constraints imposed by any locati on, always
ensure the maximum se paration possible between di fferent items of
electrical equipment.

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ii

For optimum EMC performance, it is recommended that wherever
possible:

• Raymarine equipment and cables connected to it are:

• At least 3 ft (1 m) from any equi pment transmitting or cables c arrying
radio signals e.g. VHF radi os, cables and antennas. In the case of S SB
radios, the distance should be increased to 7 ft (2 m).

• More than 7 ft (2 m) from the path of a radar beam. A radar beam can
normally be assumed to spread 20 degrees above and below the
radiating elem ent.

•The equipment is supplied from a separate battery from that used for

engine start. Voltage drops below 10 V in the power supply to our prod­ucts, and starter motor tr ansients, can cause the eq uipment to reset. This
will not dam age the equi pment, but may cause the lo ss of some inf orma­tion and may c hange the operating mo de.

• Raymarine specified cables are used. Cutting and rejoining these cables
can compromise EMC performance and must be avoided unless doing so
is detailed in the installation manual.

• If a suppression ferrite is attached to a cable, this ferrite should not be
removed. If the fe rrite needs to be rem oved during instal lation it must be
reassembled in the same position.

Suppressio n Ferrites

The following illustra tion shows typical cab le suppression ferrites used with
Raymarine equipment. Always use the ferrites supplied by Raymarine.

Connections to Other Equipment

If your Raymarine equipment is to be connected to other equipment using a
cable not supplied by Raymarine, a suppression ferrite MUST always be
attached to the cable near the Raymarine unit.

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Contents

Preface ........ ............................ ............................ ........................ i

CAUTION: Electrical safety ........................................ i

Important inf ormation ............... ......................... ................... i

EMC Installat ion Guidelines ................ ......................... ......... i

Suppression Ferrit es ........ ......................... ....................... ii

Connections to Other Equipment ................ .................... ii

Introduction ............................................................................... 1

Inputs & outpu ts ...... ......................... .......................... ............... 1

NMEA inputs ................... ............................ ......................... 2

Input priorit ies ........................ .......................... ............... 2

NMEA outputs .. ........................... ............................ ............. 2

Installation ................................................................................ 3

Mounting ............................................................................. 3

Connections ......................................................................... 4

Real-time or bu ffered inputs .............. ......................... ..... 4

NMEA in ... ......................... .......................... .................... 4

NMEA out ...... ............................ ............................ ............... 5

Power supply .......................... ............................ .................. 6

CAUTION: Electrical Safety ....................................... 7

Securing cabl es ..................... ......................... ....................... 7

Indicators .. ............................ ............................ ......................... 7

Data indicat or lit ................ .......................... ......................... 7

Overflow ind icator lit ......... .......................... ......................... 7

Both indicat ors lit ...................... ......................... .................. 8

Maintenance ............................................................................. 8

Disposal ..................................................................................... 8

Specifications ............................................................................ 9

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Introduction

The Raymarine NMEA Multiplexer combines data from up to four
NMEA-0183 devices to provide a single, multiplexed NMEA
output.

Inputs & outputs

The NMEA Multiplexer h as:

• Four NMEA inputs (listener-ports), NMEA In 1, 2, 3 & 4.

• One NMEA output (talker-port), NMEA Out

• One common terminal NMEA Out C om.

NMEA In 1a
NMEA In 1b
NMEA In 2a
NMEA In 2b
NMEA In 3a
NMEA In 3b
NMEA In 4a
NMEA In 4b
NMEA In Shld

NMEA Out a
NMEA Out b
NMEA Out Com
NMEA Out Shld

Not used

PWR +12/24V
GND

Overflow

NMEA-0183 Multiplexer

1

Data

D7684-1

2

NMEA inputs

Each NMEA in (listener) port is a differentia l pair across
terminals a and b, and can receive NMEA data from one device.
The speed of each listener p ort is fixed at 4800 baud.

NMEA data on listener ports 1
(i.e. unbuffered).

NMEA data on listener ports NMEA In 3
discrete buffer for each port. Each buffer holds approximately
2 se con ds o f NM EA dat a.

and 2 is multiplexed in real time

and 4 is fed via a

Input priorities

Data at the listener ports is prio ritized, so that eac h NMEA in
port is read tw ice as often as the next on e. Thus for example, data

1 is read in twice as often as data at input 2, four times as

at input
often as input

3 and eight times more often than input 4.

NMEA outputs

The NMEA Out (talker) port is a differential pair across terminals
a and b, and feeds mult iplexed NMEA data from all the NM EA

inputs, to up to four products.

Installation

Mounting

As the NMEA Multiplexer is not waterproof, it must be fitted in a
location where it wi ll not come into contact wit h water.

Secure the NMEA Multiplexer to a suitable surface, as shown in
the following il lustration.

Place the NMEA Multiplexer at

1.

the intended location and mark
holes for fixing screws.

Data

O

verflow

NMEA-0183 Multiplexer

Countersink pilot holes to

3.

prevent damage to the
mounting surface.

Drill two 1/8"(3.4 mm) pilot

2.

holes for NMEA Multiplexer
screws.

Secure the NMEA

4.

Multiplexer with the

screws provided.

D

ata

O

verflow

NMEA-0183 Multi

3

plex

er

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4

Connections

Real-time or buffered inputs

Be for e co nne cti ng N MEA in put s to you r NM EA M ult ip lex er,
co nsi der whe the r th ey sho uld be c onn ect ed a s re al t im e or
buffered inputs:

• Data running at a fast rate and consi sting of single sentences,
particularly time-critical data, should be connected to either
NMEA In 1 or NMEA In2, real time inputs. This includes
data from device s such as Fast Heading Sensors, and Fl uxgate
Compasses. When data is processed in real time, some sen­tences may be lo st, but the timing of the dat a is maintained
and there is no t ime delay. These inputs will sto re only one
NMEA sentence at a time, and thus prevent unwanted delays.

• Slower data that is input as a burst should be connected to
either NMEA In 3
includes data such as GPS, route and depth informati on, for
which the timing is less critical. These inputs can stor e multiple
sentences (12 to 70, depending on length). This is necessary
for devices such as GPS, which can output 10 sentences at
once, every 1 or 2 seconds.

NMEA in

Connect an unused pair of NMEA In a and b terminals on the
NMEA Multiplexer to the NMEA output port of each device from
which you wish t o receive NMEA data. The manner in which the
connections a re made depends on whether th e device has a
differential or single ended output, as f ollows:

or NMEA In 4, as buffered inpu ts. This

Device with

differential NMEA output

& shield connection

NMEA out +

NMEA out -

Shield

Cable
shield

5

NMEA Multiplexer

NMEA In a

NMEA In b

Device with

differential NMEA output

but no shield connection

NMEA out +

NMEA out -

Note: NMEA outputs from Raymarine products are differential.

Device with

single-ended NMEA output

NMEA out +

Ground

Cable
shield

Cable
shield

NMEA Multiplexer

NMEA In a

NMEA In b

Shld

NMEA Multiplexer

NMEA In a

NMEA In b

NMEA out

Connect the a and b terminals of the NMEA Out connector to
th e li ste nin g po rts of u p to fo ur d evi ces to w hic h yo u wi sh t o
transmit multiplexed data. The manner in which the connections

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are made depends on whether the device has a differential or
single ended output, as follows:

NMEA Multiplexer

NMEA Out a

NMEA Out b

Shld

Note: NMEA inputs on Raymarine products are differential.

NMEA Multiplexer

NMEA Out a

NMEA Out Com

Shld

Cable
shield

differential NMEA input

Cable
shield

single-ended NMEA input

Device with

NMEA in +

NMEA in -

Device with

NMEA in +

Ground

Power supply

The NMEA Multiplexer oper ates from a dc supply voltage in t he
range 8 V to 30 V and provides protection against reversed
polarity. It is recommended to connect the NMEA Multiplexer to
the same power source or circuit breaker as the ships instruments
and/or computer.

Protect th e power supply with a 0 .5 A fuse. The wires used to
connect the pow er supply must be less than 50 m in length and
have a total cross-sectional area of at least 0.2 mm
following exam ples represent the minimum requ irement:

2

. The

D7586-1

• 24 AWG single-strand wire.

• 7/0.2 multi-strand wire, i.e. 7 stran ds, each of 0.2 mm diame­ter

CAUTION: Electrical Safety

Before connecting power to the NMEA Multiplexer,
turn off the power supply.

Connect either a 24 V or 12 V power supply, via a 0.5 A fuse, as
follows:

+12 V or +24 V

0.5 A fuse

0 V

NMEA Multiplexer

PWR +12/24V

GND

Securing cables

When you have connected all cables, use appropriate cable ties
and/or clamps to make sure the cables are physically secure and
cannot be accide ntally pulled from their co nnectors.

Indicators

Data indicator lit

A green Data LED bli nks when valid NMEA data is received at the
listener port s, to indicate satisfactory conne ction and polarity of
the connected device. The Data LED will not blink if th e input
polarity is reversed.

Overflow indicator lit

A red Overflow LED indicates a buffer overfl ow, i.e. that more
data is coming in than can be transmitted. When a buffer is full,

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partially received sentences will be discarded, to ensure that the
NMEA Multiplexer only passes complete and valid sentences.

You may be able to resolve this o verflow situation if you:

• Set up the devices on the listener ports to send less data or
data at greater intervals. If possible, disable non-relevant sen­tences.

• Swap the input devices to different listener ports.

Both indicators lit

Both LED s will bli nk once when power is applied to the NMEA
Multiplexer. If the red LED stays lit, this indicates that a hardware
error was found during self-test.

Maintenance

There are no user-serviceable parts i nside the Raymarine NMEA
Multiplexer. However periodically check to ensure that the
connections to it are secure, and that the condition of the
connecting cables is satisfactory.

Disposal

Wh en y ou w ant to d isp ose of this pr odu ct, do s o in acc ord anc e
with local regulations.

Specifications

Supply voltage: 8 V to 30 V dc, protected against re versed

Supply protection: 0.5 A fuse

Supply connection: Minimum requirement either:

Current consumption: 70 mA maximum, with fully loaded talker ports.

Inputs: 4 x NMEA-183, galvanically isolated.

Input resistance: >800 Ohm.

Outputs: 1 x NMEA-183.

Buffers: 2 buffers of 1000 characters (NMEA In 3 and

NMEA Out: Combined data from NMEA inputs.

Speed NMEA in: 4800 baud.

Speed NMEA out: 4800 baud.

Indicators: Overflow and Data LEDs.

Dimensions: 138 x 72 x 33 mm.

Housing: Flame retardant ABS.

polarity.

24 AWG single-strand wire.
or
7/0.2 multi-strand wire.

NMEA In 4 only).

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Raymarine UK Ltd,

Quay Point,
Northarbour Road
Ports mouth ,
Hampshire PO6 3TD,
United Kingdom.
Tel: [phone]
Fax: [phone]

www.raymarine.com

Raymarin e Inc,

22 Cotton Road,
Unit D, Nashua,
New Hampshire 03063-4219,
USA.
Tel: [phone]
Fax: [phone]

www.raymarine.c om