NDC comm NDC-3 - Manual (Page 4)

Page 4 © 2005 Active Research Limited
Important Notices
The Actisense™ NMEA Data Combiner (NDC-3) is
intended for use in a marine environment, primarily for
below deck use. If the unit is to be used in a more severe
environment, such use may be considered misuse under
the seller’s warranty.
The Actisense™ NMEA Data Combiner (NDC-3) has been
certified to comply with the European directive for Electro-
Magnetic Compatibility (EN60945), and is appropriately CE
marked. Operation of the unit should be in conjunction with
appropriate CE approved shielded connectors and cabling
used in accordance with the CE directive EN60945. Any
EMC related issues should be reported to Active Research
immediately to allow the company to rectify or resolve
EMC related problems in accordance with its obligations
under EN60945.
If the unit is connected such that compliance failure occurs
beyond the company’s control, the company shall not be
held responsible for compliance failure until suitable EMC
guidelines for connection are seen to have been taken.
Notices
When using this document, keep the following in mind:
The products described in this manual and the specifications
thereof may be changed without prior notice. To obtain up-
to-date information and/or specifications, contact Active
Research Limited or visit the Actisense™ website (www.
actisense.com).
Active Research Limited will not be liable for infringement
of copyright, industrial property right, or other rights of a
third party caused by the use of information or drawings
described in this manual.
All rights are reserved: The contents of this manual may
not be transferred or copied without the expressed written
permission of Active Research Limited.
Active Research Limited will not be held responsible for
any damage to the user that may result from accidents
or any other reasons during operation of the user’s unit
according to this document.
The NDC-3 does not validate the NMEA data it receives
in any way. Neither the NMEA sentence checksum, nor
the data contained within the NMEA sentence is validated.
Therefore, the electronic device(s) supplying the NDC-3
with NMEA data retain(s) the sole responsibility for the
NMEA data’s validity.
Foreword
Actisense™ recognises that instructions are often
skipped, so we have aimed to write this document in an
informative, yet direct manner that will aid the user. We
have tried to cover all the points a typical user may need to
know. Please read all sections before installing and using
the Actisense™ NMEA Data Combiner product and any
related software programs.
Introduction
The Actisense™ NMEA Data Combiner (NDC-3) product
developed out of the requirement to solve two fundamental
problems with the existing marine industry NMEA 0183
communications standard.
In theory, the NMEA 0183 standard allows any suitably
designed marine electronic device to share its gathered
information with any other device on a vessel. Unfortunately,
there is one very large drawback with this standard - only
one device on a connected network can actually send
data (a single talker), with multiple devices (determined by
the current limit of the sending unit) listening to that data
(multiple listeners).
If the vessel owner has an instrument that ideally requires
the data output of two or more devices, for example a chart
plotter, then the owner has no alternative but to settle on
connecting only the most important device (that which
supplies the most used information), normally that is the
GPS unit. All other devices cannot be used.
What happens if the owner prefers the vessels gyro
compass heading output to that of the GPS, or requires
that the current depth be displayed on the plotted chart to
help avoid the possible case of running the vessel aground
on a shifting sand bank? The NMEA 0183 standard cannot
supply an answer to those questions as it can handle only
one transmitting device.
These two elementary problems can be solved simply and
easily with the Actisense™ NMEA Data Combiner’s very
flexible design approach.
Alternately, if the vessel has two or more identical NMEA
devices (e.g. GPS’s or depth sounders) the system solution
could be to use the Actisense™ NMEA Autoswitch.
Full information on the complete Actisense™ product
range can be found on the Actisense™ website .