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© 2009 Active Research Limited
Important Notices
Actisense
and the Actisense logo are registered
trademarks of Active Research Limited. All rights are
reserved. The contents of this manual may not be
transferred or copied without the expressed written
permission of Active Research Limited. All other
trademarks are the property of their respective owners.
The
Actisense
USB to Serial Gateway (USG-1-485)
is intended for use in a marine environment, but only
below decks. 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
USG-1-485 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
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.
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
USB to Serial Gateway product.
Introduction
The
Actisense
USB to Serial Gateway (USG-1-485)
product developed out of the requirement to solve three
fundamental problems with interfacing the industry RS485
communications standard to a PC.
These are:
1.
Ground loops
. When the PC and the connected
system have different ground potentials (or are
totally different ground altogether), data can become
corrupted and permanent damage can occur.
2.
Different standards
. When you buy a standard USB
to serial converter, they normally provide PC standard
RS232 port, whereas RS485 uses a differential bi-
directional signalling system. This means that a
standard USB to serial converter is incompatible with
RS485 / IEC61162-2 that uses the RS485 electrical
driver type.
3.
PC has no serial port.
Most modern PCs do not
come with serial ports any more as these are being
replaced by the new standard of USB. Furthermore,
RS485 signals are not directly compatible with
standard PC serial ports.
Full information on the complete
Actisense
product range
can be found on the
RS485 & IEC61162-2
The port provided by the USG-1-B-485 will be referred
throughout the document as “RS485” although the
IEC61162-2 marine standard uses the same interface,
and the two terms are interchangeable.
The IEC61162-2 interface is not normally used in a
bidirectional mode, however, and is generally referred to
as a three-wire RS422 system. The differential signalling
method and the output driver levels are compatible
between the two systems.
Summary of Contents for USG-1-B-485
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