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NMEA Multiplexer
Owner’s Handbook
Document Number: 81250-1
Date: February 2005
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© Copyright Raymarine (UK) Ltd 2005
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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. However, Raymarine cannot accept liability for any inaccuracie
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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 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. •The equipment i
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iii Contents Preface ........................................................................................ i CAUTION: Electrical safety ........................................ i Important information ........................................................... i EMC Installation Guidelines .................................................. i Suppression Ferrites ........................................................ ii Connections to Other Equipment .................................... ii
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Data Overflow NMEA-0183 Multiplexer 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. 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 O
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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. Input priorities Data at the listener ports is prioritized, so that each NMEA
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Data Overflow NMEA-0183 Multiplexer Data Overflow NMEA-0183 Multiplexer 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 2. Drill two 1/8"(3.4 mm) pilot the intended location and mark holes for NMEA Multiplexer holes for fixing screws. screws. Secure the NMEA
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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. When data is processed in real time, some sen- tences may be los
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5 Device with Cable differential NMEA output shield & shield connection NMEA Multiplexer NMEA out + NMEA In a NMEA In b NMEA out - Shield Device with Cable differential NMEA output shield NMEA Multiplexer but no shield connection NMEA out + NMEA In a NMEA In b NMEA out - Shld Note: NMEA outputs from Raymarine products are differential. Cable Device with shield single-ended NMEA output NMEA Multiplexer NMEA out + NMEA In a NMEA In b Ground NMEA out Connect the a and b termi
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6 are made depends on whether the device has a differential or single ended output, as follows: Cable Device with shield NMEA Multiplexer differential NMEA input NMEA in + NMEA Out a NMEA Out b NMEA in - Shld Note: NMEA inputs on Raymarine products are differential. Cable Device with shield NMEA Multiplexer single-ended NMEA input NMEA Out a NMEA in + NMEA Out Com Ground Shld Power supply The NMEA Multiplexer operates from a dc supply voltage in the range 8 V to 30 V and pro
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7 • 24 AWG single-strand wire. • 7/0.2 multi-strand wire, i.e. 7 strands, each of 0.2 mm diame- ter 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: NMEA Multiplexer 0.5 A fuse +12 V or +24 V PWR +12/24V 0 V 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
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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 sen- tences. • 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. If the red LED stays lit
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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
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10 Raymarine UK Ltd, Raymarine Inc, Quay Point, 22 Cotton Road, Northarbour Road Unit D, Nashua, Portsmouth, New Hampshire 03063-4219, Hampshire PO6 3TD, USA. United Kingdom. Tel: +1 603.881.5200 Tel: +44 (0) 23 9269 3611 Fax: +1 603.864.4756 Fax: +44 (0) 23 9269 4642 www.raymarine.com www.raymarine.com
