USG-1-A-422 User Manual issue 1.01.indd
Contents
1. E os RS465 N fan oo H 5 ami C3 tagg H i hi OACTIVE SEARCH LTD 2006 Figure 1 Inside the USG 1 case Figure 1 shows an internal view of the USG 1 Printed Circuit Board PCB The USG 1 has both micro connectors and screw terminal Phoenix type connectors 1 A micro connector attached to the standard data cable that comes with the USG 1 This cable should be sufficient for most installations The colour codes used for this cable are Sewn orro mentee a This cable also has a screen connection This is not connected inside the USG 1 in most instances simply connect this to ground at the instrument end and this will provide correct screening of the signals on the USG 1 data cable The Phoenix style connectors are provided for use when the customer needs to use their own cable O MADA B B A s OUT IN Ft aN o lt2. EARCH LTD 2006 2 An NMEA 0183 input Two screw terminal Phoenix style connectors are provided to connect the NMEA 0183 input 2006 Active Research Limited All NMEA 0183 inputs are of the differential Opto isolated type and use the unique Actisense low current drain circuitry 2mA 2 0v to conform in full with the NMEA 0183 marine electronic device network communication standard They are also flexible enough to interface to most fully and partially compliant NMEA 0183 devices 3 An NMEA 0183 ISO Drive output Three screw terminal Phoenix style connectors are provided to connect to the NMEA 0183 ISO Drive output The NMEA0183 output comprises three connections and Ground GND and conforms in full to the NMEA 0183 standard This allows the USG 1 to interface to various different devices that require any combination of these outputs Note The connection marked GND on the ISO Drive output is not USB or PC ground it is connected to the isolated ground of the ISO Drive circuit In most installations this GND should be left disconnected It is only for use in special circumstances where an RS485 or IEC61162 2 3 terminal type connection is required and is reserved only for specialist installations No damage will be caused by connecting to this GND in error but it may result in missing or corrupted data if itis used Always follow the connection diagr
3. button to save the new settings Advanced Settings for COM4 Use FIFO buffers requires 16550 compatible UART Select lower settings to correct connection problems Select higher settings for faster performance Defaults Receive Buffer Low 1 y High 14 14 Transmit Buffer Low 1 YJ High 16 16 COM Port Number COM4 2006 Active Research Limited Page 13 Actisense Troubleshooting guide This guide will concentrate on all relevant troubleshooting issues above simple cable connection faults Therefore the cables between the USG 1 hardware and any other devices should be checked as a matter of course before continuing with this guide Diagnostic LED The USG 1 hardware has a bright LED that can be seen through the case to indicate when data is either received or transmitted It can be used to debug potential problems If you have both a talker and a listener connected then you can analyse which is working by disconnecting one of them or by stopping the PC from sending data Required user response LED does not flash when the Check that the PC program is sending data and that it has opened the comms port PC is sending data assigned by user or allocated by Windows Device Manager to the USG 1 Check that the Talker device is correctly connected to the USG 1 that it is powered LED does not flash when the on and that it is sending data In addition the USB driver must be correctly Talker
4. Telephone 01202 746682 International 44 1202 746682 Fax 01202 746683 International 44 1202 746683 Actisense on the Web For advice support and product details E mail support actisense com Website www actisense com Active Research on the Web For specialist consultancy and customisation E mail support activer com Website www activer com 2006 Active Research Limited Page 16
5. 0 5 V Input voltage between Logical 0 4 0 15 0 V Maximum is under 35v overload npa gumer condition min 2 0v input level 20 ae dee eee Required level for NMEA to be Ditrerential input vokage detected from a connected talker ma a0 Galvanic isolation Between input amp output 2500 Overdrive protection 40 V ISO Drive Flexible Output Output voltage between and under no Logical 1 4 8 5 2 V load Logical 0 4 8 5 2 v Output current at max load of 100 ohm AN maximurmn toad differential dave 21 mA voltage reduces to 2 1v Output short circuit current note 1 Due to short circuit protection 50 55 mA Galvanic isolation From Opto input and USB ground 1500 V Static discharge protection PC Communication settings Both input amp output Baud rates are set Baud rate by the PC software settings Pay 1peuy Mps General Ambient temperature 20 70 C Table 2 USG 1 specifications All specifications are taken with reference to an ambient temperature T of 25 C Note 1 Short circuit may be applied indefinitely The ISO Drive output may be short circuited directly to a 30 volt battery supply without damage A maximum current of 50mA will flow due to polyfuse auto resetting fuse technology being used in each output 2006 Active Research Limited Page 15 Actisense Company Information Active Research Limited O TM 5 Wessex Trade Centre aaas Actisense Poole Dorset UK BH12 3PF
6. a typical installation with an NMEA Talker and an NMEA Listener connected to the USG 1 The NMEA Talker connections may be marked either A B or if the talker is a differential drive device or Tx GND for a single ended device Notes 1 To complete the NMEA 0183 standard all device interconnection NMEA cables used should meet the two conductor shielded twisted pair configuration specification The shield connection of these wires should be connected at the instrument end only to prevent ground loops 2006 Active Research Limited NMEA 0183 ISO Drive Output The NMEA 0183 buffered output is capable of driving up to 10 NMEA 0183 fully compliant Listening devices or a mixture of NMEA 0183 Listening devices and a Personal Computer PC communication port However it is only recommended to connect one listener to the USG 1 If multiple instruments are connected in parallel to the USG 1 there will be a chance that isolation will not be maintained between them as some of the connected devices may not have correct opto isolated inputs If the user manuals for the connected instruments indicate that all the listeners are opto isolated then they may be safely parallel connected into the ISO Drive output and safe isolation will be maintained The connections on an NMEA Listener may be marked either A B or if the Listener is a differential drive device or Rx GND for a single ended device Refer to figure 2 The groun
7. is sending data installed and the PC software must have the assigned comms port open for the LED to flash Check that the Listener device is correctly connected to the USG 1 that it is powered on and that it is set to receive data at the Baud rate of the PC comms port No data is being received by the Listener but LED is If there is a cable problem that has activated the short circuit protection the flashing as PC is sending protective poly fuses will have activated to protect the USG 1 from damage In this case remove the cable fault and wait 1 minute before reconnecting the USG 1 to the NMEA listener device If the error persists the USG 1 unit should be returned to Actisense refer to the Company Information section Please contact Actisense before returning the unit in order to obtain a Returns Number Any returns sent without a Returns Number will incur a delay in being processed Table 1 Diagnostic LED colours 2006 Active Research Limited Page 14 USB to Serial Gatewa USG 1 A 422 Specifications The USG 1 ISO Drive output is a very flexible output that is RS485 RS232 RS422 and NMEA 0183 compatible Foam onions o woe un Supply Supply voltage From USB port 4 75 5 25 V Supply voltage 5v no load 40 46 mA Supply current drawn from USB port Supply voltage 5v output shorted 75 80 mA Opto isolated Flexible Input Logical 1 15 0
8. list followed by the allocated COM port number DAR Device Manager Fie Action view Help m amp e a Se Keyboards Mice and other pointing devices Modems 2 Monitors BB Network adapters B 1394 Net Adapter 2 5 Intel R PRO Wireless 2200BG Network Connection E9 Realtek RTL8169 8110 Family Gigabit Ethernet NIC PCMCIA adapters Y Ports COM amp LPT gt A Actisense USG COM4 wo Communications Port COM1 a ECP Printer Port LPT1 MB Processors amp SCSI and RAID controllers Sound video and game controllers 4 System devices Page 12 USB to Serial Gateway USG 1 A 422 3 Double click on the port icon for the Actisense USG and the port properties window will appear Click on the Port Settings tab Here you can set the default settings for the USG 1 device It is not necessary to change the default settings here as each software program will define these settings itself Actisense USG COM4 Properties p General Port Settings Driver Details Bits per second Data bits Parity Stop bits 1 Flow control Restore Defaults 4 Click on the Advanced button and choose a different COM Port number if required to make it compatible with the software requiring the USG 1 NMEA data The othersettings are already optimised forthe Actisense USG 1 and should be left in the default values Click on OK
9. search for current and updated software by looking on your computer on the hardware installation CD or on the Windows Update Web site with your permission Read our privacy policy Can Windows connect to Windows Update to search for software O Yes this time only O Yes now and every time connect a device No not this time Click Next to continue 2 Insert the Actisense CD choose the Install from a list or specific location option and click Next Found New Hardware Wizard This wizard helps you install software for USG 1 4 C If your hardware came with an installation CD lt 9 or floppy disk insert it now What do you want the wizard to do O Install the software automatically Recommended Install from a list or specific location Advanced Click Next to continue Page 10 USB to Serial Gateway USG 1 A 422 3 Make sure the Include this location in the search option is ticked and use the Browse button to locate the USB Drivers directory on the Actisense CD Found New Hardware Wizard Please choose your search and installation options Sm Y Search for the best driver in these locations Use the check boxes below to limit or expand the default search which includes local paths and removable media The best driver found will be installed Search removable media floppy CD ROM Include this location in the search E VUSB Drivers v Brow
10. serial converter they normally provide PC standard RS232 port whereas NMEA 0183 uses a standard called RS422 This results in Incompatible voltage levels and electrical driver types 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 Full information on the complete Actisense product range can be found on the Actisense website Page 4 USB to Serial Gateway USG 1 A 422 USG 1 solutions Solution 1 Ground loops The first problem encountered when using a standard USB to serial converter or a standard RS232 port is that the ground of the PC is then shared with the NMEA 0183 system ground PCs are often powered from a mains inverter generator set or direct from mains supply when in dock whereas the marine electronics are normally connected to the current marine battery set This means that when you connect the two systems together you are joining two different power systems This can result in no visible problems but more often it results in one of three consequences 1 Data corruption the data becomes garbled as the electrical data signal now floats on a noisy ground current flowing between the two power systems 2 The PC crashes intermittently as ground currents flow across its sensitive electronic circuitry This can cause permanent damage 3 In the case of large ground loop faults some components can melt catch
11. 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 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 andthe 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
12. Actisense USB to Serial Gateway User Manual USG 1 A 422 For use with NMEA 0183 and IEC 61162 1 connections Issue 1 01 Create a safe serial port connection to an NMEA 0183 system that may be on a different power circuit Connect two PCs together that are on different power circuits Provide a fully compliant NMEA 0183 port from a USB port Receive low level differential signals that are too small to be received directly by a PC serial port USB to Serial Gateway USG 1 A 422 Contents Important Notices Notices Foreword Introduction USG 1 solutions Solution 1 Ground loops Solution 2 Different standards Solution 3 PC has no serial port Features Software updates NMEA 0183 interfacing The basics The NMEA signals The different NMEA standards Opening the USG 1 USG 1 connections Connecting NMEA 0183 devices NMEA 0183 Input NMEA 0183 ISO Drive Output Connecting to a Personal Computer RS232 port Connecting to a 3 pin RS485 Listener IEC 61162 2 9 O oo 0O N Ooo 0O OAOA anoa A A A A USB Driver Installation 10 Step by step guide 10 USB Configuration 12 Step by step guide 12 Troubleshooting guide 14 Diagnostic LED 14 Specifications 15 Company Information 16 2006 Active Research Limited Page 3 Actisense Important Notices The Actisense USB to Serial Gateway USG 1 is intended for use in a marine environment but only below decks If
13. ams shown in this manual to ensure correct operation 4 A micro connector to connect to the supplied USB type A terminated cable This connector should not normally be removed it is installed at the factory and is not customer serviceable 5 An indicator LED This LED flashes when data is sent from or received by the USG 1 It can be clearly seen through the USG 1 s translucent lid when the case is closed Page 7 Connecting NMEA 0183 devices HH EARCH LTD 2006 NMEA Talker NMEA Listener Do not connect Figure 2 NMEA 0183 connections NMEA 0183 Input The NMEA 0183 differential Opto isolated input is designed to handle a variety of NMEA 0183 device output specifications The user must determine from device manufacturer s information if the device s required to be connected to the Actisense USG 1 conforms in full to the NMEA 0183 network communication standard If it does not the flexible Actisense USG 1 inputs should still be capable of interfacing with the device though this is not guaranteed Figure 2 shows
14. d GND connection must not be connected 2 Throughout these connection diagrams the wire colours represent those actually used on the supplied Actisense USG 1 data cable When using the supplied cable simply use the colours indicated to connect to your NMEA 0183 instrument 3 Refer to the Specifications section for the full details on input output specifications Page 8 USB to Serial Gateway USG 1 A 422 Connecting to a Personal Computer RS232 port Be l EARCH LTD 2006 Figure 3 Personal Computer RS232 port connections The USG 1 can be connected to a PC communications port using a cable conforming to the following specification 1 A D type female socket connector for the PC end of the cable A minimum of 3 cores are required in a shielded cable Higher quality cable will naturally yield higher performance higher Signal to Noise Ratio SNR Most typical cables have two twisted pairs inside In this case use one pair for the TX line and one for the RX line Use the spare wire in each pair as ground and connect the cable shield to ground only at the computer end 3 The OUT A of the USG 1 should be connected to
15. e base of the unit and the two supplied cables attached to their connectors Note When opening the USG 1 case be aware that the circuitry inside is not 100 protected against static electricity Please ensure that when opening the case you use precautions against static damage by only touching the connector block and by holding the unit by its base In this way the risks of static damage will be minimised Page 6 USB to Serial Gateway USG 1 A 422 USG 1 connections io fmi E O am aaa meoin N IN A B OUT OUT IN A B on mi a8 Q Annan C f cara H 3 CONGND oS
16. e with RS232 signal levels The Opto isolator can thus protect any upstream equipment chart plotter laptop PC radar etc from up to 2500v of common mode voltage difference PC USB drivers supplied on disc the drivers allow the USG 1 to appear as a standard COM port on the PC Low current consumption the USG 1 is powered directly from the USB port on your PC so no extra power cables are required Tough Polycarbonate case certified to IP54 Splash and dust proof when used with both supplied cables Software updates The USG 1 has no built in firmware but Actisense will be providing updates to the PC USB drivers free on our website www actisense com when they become available Page 5 Actisense NMEA 0183 interfacing The basics NMEA data is transmitted from an information source such as GPS depth sounder gyro compass etc These data sending devices are called Talkers Equipment receiving this information such as a chart plotter radar or NMEA display is called a Listener Unfortunately only one Talker can be connected on to a single NMEA 0183 system at any one time Two or more Talkers are simply not possible because they are not synchronised to each other and will attempt to talk at the same time over each other resulting in corruption of the NMEA data and potentially in disaster if valuable data such as navigation information is lost or corrupted so that it is incorr
17. ect and or misleading Actisense produces a full range of products to solve all NMEA interfacing requirements Please visit the Actisense website for full details on these and other Actisense interfacing products NMEA Multiplexers NMEA Buffers and NMEA Autoswitches Depth sounders and Sonar products The NMEA signals The NMEA 0183 system v2 0 and later uses a differential signalling scheme whereby two wires are used to transmit the NMEA data These connections will be labelled as either NMEA A and B or NMEA and respectively depending on the instrument and manufacturer When connecting between different manufacturers there can be some confusion but it is simple and easy to remember NMEA A connects to NMEA and NMEA B connects to NMEA The different NMEA standards The NMEA 0183 specification has slowly evolved over the years so connecting one device to another is not always a straightforward matter The earlier versions of NMEA 0183 before v2 0 as detailed above used slightly different connection methods and signal levels the instruments had just one NMEA data line Tx or Out and used the ground as the other line similar to the way a computer serial port works This connection method is referred to as single ended instead of the differential method used by NMEA 0183 v2 0 devices The data format is largely the same be
18. fire fuses blow or earth leakage devices trip The USG 1 solves all these problems by providing a safe opto isolated barrier between the two systems Because the signal travels across this barrier as light the signals do not share the same ground and safety is assured as no current can flow between the two power systems In addition a built in power isolator completes the isolation Solution 2 Different standards PC serial or COM ports use the RS232 standard This uses a ground and a receive pin to get data from a connected system Data is sent as voltages referenced to ground on a single transmit line This type of drive is known as single ended In contrast NMEA 0183 systems use a differential system where a Positive data line and a Negative data line move in opposition to each other Many installations without isolated outputs have been seen where the negative data line on a differential drive system has been connected to the ground of the PC If you re lucky this may work but if not you will either simply get no data or at worst damage your equipment The USG 1 solves this by using ingenious circuitry unique to Actisense in both it s Listener receiver circuit and its ISO Drive Talker transmitter circuit These circuits are compatible with both RS232 and NMEA 0183 types Please refer to the NMEA 0183 Interfacing section for more information on Talkers and Liste
19. kes the USB connection appear as a COM port in the Windows Device Manager The USG 1 with USB connection has been extensively tested with both Windows XP and Windows 98 SE For the experienced Windows XP user who is used to installing drivers this section will be very familiar To all other Windows users the required steps are detailed below to help with installation The steps for Windows 98 SE are very similar to those of Windows XP and so are not detailed here The Actisense CD also contains the USB drivers for Windows 2000 These drivers have not been tested by Actisense but should operate in the same manner as the Windows 98 SE and XP drivers The required Linux drivers are already included in the Linux kernels from v2 4 20 and onwards However Actisense has not been able to test the compatibility of the USG 1 with USB and this driver For MAC OS 8 9 and X please contact Actisense for details refer to the Company Information section 2006 Active Research Limited Step by step guide 1 Make sure the Actisense USG 1 is connected to an available USB port on the PC The standard Windows Found New Hardware Wizard window will then appear Select the No not this time option to allow driver installation from the Actisense CD which was supplied with your Actisense product Found New Hardware Wizard Welcome to the Found New Hardware Wizard Windows will
20. nd New Hardware Wizard The wizard has finished installing the software for Actisense USG USB Serial Gateway Click Finish to close the wizard This second wizard will guide you through the USB Serial Port driver installation 6 Follow steps 1 to 5 above for the USB Serial Port driver installation and click Finish to complete Your new hardware is installed and ready to use will appear in the bottom right corner of your screen when the installation is complete See the USB Driver Configuration section for details on how to find out which COM port number has been allocated to your Actisense device as well as how to change to a different COM port and configure the Baud rate x i Found New Hardware Your new hardware is installed and ready to use Page 11 Actisense USB Configuration To communicate with the USG 1 the COM port number that Windows has allocated to the USB port needs to be determined The following guide will walk the user through this standard operation The Actisense USB to Serial Gateway USG 1 is completely USB port independent it can be easily unplugged from one USB port and connected to another available USB port on the same PC without the COM Port number changing To achieve this independent operation plug the USG 1 into each required USB port that you require it to work with in turn install the USB drivers and manually change the allocated COM port
21. ners 2006 Active Research Limited Solution 3 PC has no serial port Many laptop and desktop PCs do not come equipped with RS232 type serial ports any more The USG 1 creates a marine standard NMEA 0183 port from any PC USB port This port appears on the PC system as a regular COM port and so can be used with all standard navigation and display software Features Standard USB connection Equipped with a type A USB connector to connect to a USB port or hub USB v1 1 or v2 0 compliant ISO Drive output technology creates a driver unique to Actisense that is isolated to 1500 volts say goodbye to ground loop issues ISO Drive allows a completely floating output to be created making a safe connection to a PC an easy task You can use the SO Drive output to safely transfer data to an NMEA 0183 device or to another PC The output automatically changes between differential and single ended drive depending upon the type of instrument it is connected to NMEA 0183 OPTO input a floating receiver opto isolated to 2500 volts protects your system even during the most extreme fault conditions This differential input is fully compliant with the NMEA 0183 standard specification This allows the USG 1 to work correctly with long cable runs and in a noisy environment Typical operating voltage is 2 0v to 15 0v The unit can withstand 35v continuously and 40v transients The input is also compatibl
22. number to the same number for each USB port Once configured the COM port number will not change unless instructed to do so by the user This is very useful when the USG 1 is working in unison with a software program that is set up to use a particular COM port as the user does not need to reselect a different COM port every time the PC reboots or the cable is swapped between two USB ports 2006 Active Research Limited Step by step guide 1 Make sure the Actisense USG 1 is connected to an available USB port on the PC From the Windows Control Panel open the System Properties window and click on the Hardware tab System Properties Remote Advanced System Restore General Automatic Updates Computer Name Hardware Device Manager x The Device Manager lists all the hardware devices installed on your computer Use the Device Manager to change the properties of any device Drivers Driver Signing lets you make sure that installed drivers are compatible with Windows Windows Update lets you set up how Windows connects to Windows Update for drivers Driver Signing Windows Update Hardware Profiles Hardware profiles provide a way for you to set up and store different hardware configurations Hardware Profiles 2 Click on Device Manager and expand the Ports COM amp LPT list by clicking on the sign next to it You will find the Actisense USG in the
23. se Don t search will choose the driver to install Choose this option to select the device driver from a list Windows does not guarantee that the driver you choose will be the best match for your hardware lt Back Next gt Cancel 4 The Actisense USB Serial Converter driver is not Microsoft Windows certified but it has been tried and tested for stable and reliable operation with the Actisense USG 1 Click Continue Anyway to carry on with the installation Found New Hardware Wizard Please wait while the wizard installs the software rad Actisense USG USB Serial Gateway Hardware Installation The software you are installing for this hardware Actisense USG USB Serial Gateway has not passed Windows Logo testing to verify its compatibility with Windows XP Tell me why this testing is important Continuing your installation of this software may impair or destabilize the correct operation of your system either immediately or in the future Microsoft strongly recommends that you stop this installation now and contact the hardware vendor for software that has passed Windows Logo testing Continue Anyway STOP Installation 2006 Active Research Limited 5 The USB Serial Converter driver is now installed click Finish to complete the wizard and wait for the Found New Hardware Wizard to appear again Found New Hardware Wizard Completing the Fou
24. the RX of the computer standard D type pin 2 and the USG 1 IN A should be connected to the TX of the computer pin 3 Connect the IN B and OUT B together and connect to the PC s serial port ground pin 5 Connecting to a 3 pin RS485 Listener IEC 61162 2 H O BH l EARCH LTD 2006 RS485 Listener Figure 4 RS485 IEC 61162 2 port connections The USG 1 ISO Drive output can be connected to an RS485 Listener that requires differential drive plus ground as shown in figure 4 2006 Active Research Limited Page 9 Actisense USB Driver Installation The Actisense USG 1 makes use of a virtual serial port driver know as the Virtual COM Port Driver to interface between the USB port on the PC and the Actisense product This driver allows software running on a PC to communicate with the Actisense USG 1 as if it was connected to a standard serial port on the PC when in fact all communication is done over the USB connection The required driver installation comes in two separate packages The first driver is a called the Serial Converter which converts the USB data packets to a serial data stream The second driver called the Actisense USB Serial Port ma
25. tween both systems with v2 0 adding some extra sentence strings and removing older redundant sentence strings from the specification The situation is further complicated as many manufacturers still use the old single ended method of connection because it is cheaper to implement The Actisense USG 1 solves all NMEA 0183 connection 2006 Active Research Limited issues by having inputs and outputs that are totally compliant with both systems and which float independently from ground at all times By following the simple connection diagrams in this manual the user can be safe in the knowledge that as long as the connection is secure the data will go through as intended and no damage will result Please refer to the Connecting NMEA 0183 devices and Connecting Personal Computer RS232 port sections for example of these connection methods Opening the USG 1 The USG 1 comes supplied with a factory installed connection cable with tinned solder wire ends Using this cable means that you will not need to open the USG 1 case to make your connections If you need to use your own cable Phoenix style connectors are provided within the USG 1 to allow you to connect it To open the USG 1 remove the two screws in the base of the USG 1 then slide off the top of the USG 1 case The grommets need to be slid off the top of the case in order to access the internal connections You will be left with the USG 1 circuitry attached to th
26. 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 When used on an NMEA 0183 system the USG 1 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 USG 1 with NMEA data retain s the sole responsibility for the NMEA data s validity 2006 Active Research Limited 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 product developed out of the requirement to solve three fundamental problems with interfacing the marine industry NMEA 0183 communications standard to a PC These are 1 Ground loops When the PC and the NMEA 0183 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
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