NMEA Multiplexer Owner’s Handbook Document Number: 81250-1 Date: February 2005
© Copyright Raymarine (UK) Ltd 2005
i Preface Congratulations on having bought a Raymarine NMEA Multiplexer. This enables you to combine 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 information To the best of our knowledge, the information in this handbook was correct when it went to press.
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 equipment transmitting or cables carrying radio signals e.g. VHF radios, cables and antennas. In the case of SSB 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 element.
iii Contents Preface ........................................................................................ i CAUTION: Electrical safety ........................................ i Important information ........................................................... i EMC Installation Guidelines .................................................. i Suppression Ferrites ........................................................ ii Connections to Other Equipment ....................................
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1 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 has: • Four NMEA inputs (listener-ports), NMEA In 1, 2, 3 & 4. • One NMEA output (talker-port), NMEA Out • One common terminal NMEA Out Com.
2 NMEA inputs Each NMEA in (listener) port is a differential pair across terminals a and b, and can receive NMEA data from one device. The speed of each listener port is fixed at 4800 baud. NMEA data on listener ports 1 and 2 is multiplexed in real time (i.e. unbuffered). NMEA data on listener ports NMEA In 3 and 4 is fed via a discrete buffer for each port. Each buffer holds approximately 2 seconds of NMEA data.
3 Installation Mounting As the NMEA Multiplexer is not waterproof, it must be fitted in a location where it will not come into contact with water. Secure the NMEA Multiplexer to a suitable surface, as shown in the following illustration. 1. Place the NMEA Multiplexer at the intended location and mark holes for fixing screws. 2. Drill two 1/8"(3.4 mm) pilot holes for NMEA Multiplexer screws. Da ta Ov erflo w EA -01 83 Mu ltip lex er 3.
4 Connections Real-time or buffered inputs Before connecting NMEA inputs to your NMEA Multiplexer, consider whether they should be connected as real time or buffered inputs: • Data running at a fast rate and consisting 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 devices such as Fast Heading Sensors, and Fluxgate Compasses.
5 Device with differential NMEA output & shield connection Cable shield NMEA Multiplexer NMEA out + NMEA In a NMEA out - NMEA In b Shield Device with differential NMEA output but no shield connection Cable shield NMEA Multiplexer NMEA out + NMEA In a NMEA out - NMEA In b Shld Note: NMEA outputs from Raymarine products are differential.
6 are made depends on whether the device has a differential or single ended output, as follows: NMEA Multiplexer Cable shield Device with differential NMEA input NMEA Out a NMEA in + NMEA Out b NMEA in - Shld Note: NMEA inputs on Raymarine products are differential.
7 • 24 AWG single-strand wire. • 7/0.2 multi-strand wire, i.e. 7 strands, 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: 0V NMEA Multiplexer PWR +12/24V GND D7588-1 0.
8 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 overflow 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 blink once when power is applied to the NMEA Multiplexer.
9 Specifications Supply voltage: 8 V to 30 V dc, protected against reversed polarity. Supply protection: 0.5 A fuse Supply connection: Minimum requirement either: 24 AWG single-strand wire. or 7/0.2 multi-strand wire. 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 In 4 only). NMEA Out: Combined data from NMEA inputs.
10 Raymarine UK Ltd, Quay Point, Northarbour Road Portsmouth, Hampshire PO6 3TD, United Kingdom. Tel: +44 (0) 23 9269 3611 Fax: +44 (0) 23 9269 4642 www.raymarine.com Raymarine Inc, 22 Cotton Road, Unit D, Nashua, New Hampshire 03063-4219, USA. Tel: +1 603.881.5200 Fax: +1 603.864.4756 www.raymarine.
