User manual

NMEA Data Multiplexer - NDC-4
Page 5© 2011 Active Research Limited
General Features
4/5 Opto-isolated Input Ports
Each Opto-isolated input port has a priority level. This
defaults to the logical order matching the port numbers,
i.e. port 1 has the highest priority and port 4 has the lowest.
WhentheUSBcableisnotpluggedin(ornotpowered),
OPTOIN0can beused as afth fullycompliantNMEA
0183 data input, appearing last in the priority list.
2 ISO-Drive Output Ports
TheseoutputscombinetheinputdataintostandardNMEA
outputs with independent Baud rate selection options,
defaulting to 4800 (OUT 1) and 38400 (OUT 0). If the
combinedBaudrateofallNMEAinputsexceedtheoutput
Baud rate, it is possible that the combined data could
exceed the data carrying capacity of the NMEA output
channel. The multiplexer contains special software to
ensure that when the output channel is overloaded, new
dataofthesametypeasolderdata,stillinthebuffer,will
overwrite the older sentence.
A PC RS232 or USB Bidirectional Port
TheRS232compatiblePort0(OPTOIN0plusISOOUT
0) and the USB interface ensures that any device (or PC),
that has an RS232 or USB port, receives all the input
NMEA data, and can add its own NMEA data to ISO OUT
1. This allows for the possibility of a “virtual cockpit” of
instrumentsdisplayingallavailabledatainanymannerthe
userrequires(availablefromanumberofmanufacturers).
Theseconnectionsalsoallowthe unit to beupdatedvia
thefreelyavailableActiPatchashupgradesoftwarethat
willbemadeavailableontheActisensewebsitewhenthe
NDC-4rmwarehasbeenenhanced.
Notes:
1. WhentheUSBcableispluggedinandpoweredup,it
disablesOPTOIN0ontheNDC-4.
2. NDC-4variantsthatdon’tcomewithaUSBcablecan
beupgradedbypurchasingaUSBUpgradeKit.
Technical Features
Flash ROM technology that supports automatic
programming for quick and easy updates, 100,000+ erase
cycles and a 10 year Data Retention provides carefree
userconguration.
On-chip memory store allows buffering of short-term
NMEA data, allowing the unit to smooth short-term peaks
intheNMEAdataow.
A diagnostic LED indicates the operation mode of the
NDC-4,ifanyfaultshavebeendetected,orthepeakload
currently on any one of the NMEA inputs.
High-speed 32-bit ARM processorcapableofupto40
million instructions per second.
The NMEA 0183 inputs are galvanically opto-isolated
differential inputs, protecting against common mode
voltage differences of up to 2500v. Fully compliant with the
NMEA 0183 standard specication and compatible with
RS232, RS422 and RS485 signal levels. The typical
operating voltage is 2.0v to 15.0v and can withstand +/-
35vcontinuouslyand+/-40vtransients.Compatiblewith
bothdifferentialandsingleendedinputs.
ISO-Drive output technology unique to Actisense,
protects against common mode voltage differences of up
to 1500v. The output automatically changes between
differential and single ended drive depending upon the
type of instrument it is connected to. Fully compliant with
the NMEA 0183 standard specication and compatible
with RS232, RS422 and RS485 signal levels.
Wide battery input voltage range to offer maximum
compatibility,theNMEA0183NDC-4canoperatefroma
batterysupplyanywherebetween8and35volts.
USB poweredoptionisavailablewhenthebatterysource
isnotpresent.Whenthemainbatteryispresent,theUSB
power drain is minimal. WARNING:TheUSBandbattery
grounds are not isolated, see “USB Warning” on page 9.
Very tough Polycarbonate case is certied to IP66
(Protectionagainstheavyseas,orpowerfuljetsofwater),
the addition of non-acid based marine sealant to the
gasket can increase this to IP67 (Protection against
immersion). Being Polycarbonate, it is also incredibly
strong, offering a wide temperature range and superior
protection to the electronics inside.
Robust Nylon grommetsarecertiedtoIP68(Protection
againstcomplete,continuoussubmersioninwater).
Note: To achieve this level of water integrity all glands
must be occupied by round-section cables of between
4.5mmand10mmorbereplacedbyblankingplugs.
Large range of possible cable diameters of between
4.5mmand10mm,singleormulti-pairwiretypescanbe
easily accepted.
Software Updates
The NDC’s built-in rmware is held in ‘ash’ memory,
allowing quick and easy upgrades using a simple Microsoft
Windows™ NT/2000/XP/Vista/7 user interface program
(ActiPatch) running on a connected PC.
It is our policy to provide these updates free on the
Actisense website (www.actisense.com). This upgrade
canbeperformedwiththeunitcompletelyin-situ,viaaPC
connected to either Port 0 (OPTO IN 0 and ISO OUT 0) or
the USB port.