User manual

NMEA Data Multiplexer - NDC-4-A & NDC-4-A -USB
Page 7© 2009 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.
If the USB cable is not plugged in (or not powered) and
OPTO IN 0 is not used to connect to a PC, OPTO IN 0 can
be used as a fth fully compliant NMEA 0183 data input.
2 ISO-Drive output ports
These outputs combine the input data into standard
NMEA outputs. 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 bi-directional 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 the
combined output. 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.
When the USB cable is plugged in and powered up, it
disables the OPTO IN 0 on the NDC. For example this
is very useful when a PC is supplying data, and you
want an NMEA device to supply the same data when
the PC is powered down.
Note that standard NDC-4 units can be upgraded to USB
by purchasing a USB upgrade kit.
Technical features
High-speed 32-bit ARM processor capable of up to 40
million instructions per second.
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.
The NMEA 0183 inputs are oating receivers, opto-
isolated to 2500 volts, protecting your system even during
the most extreme fault conditions. This differential input is
fully compliant with the NMEA 0183 standard specication
and is also compatible with RS232 signal levels. Typical
operating voltage is 2.0v to 15.0v. The unit can withstand
+/- 35v continuously, and +/- 40v transients. The Opto-
isolator can thus protect any upstream equipment (chart
plotter, laptop PC, radar etc.) from up to 2500v of common
mode voltage difference.
ISO-Drive output technology creates a driver, unique to
Actisense, that is isolated to 1500 volts. ISO-Drive allows
a completely oating output to be created, making a safe
connection to a PC an easy task. The output automatically
changes between differential and single ended drive
depending upon the type of instrument it is connected to.
The ISO-Drive output is fully compliant with the NMEA
0183 standard specication and is also compatible with
RS422 & RS232 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.
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.
Very tough Polycarbonate case is certied to IP66
(splash-proof). 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
(submersible). Note that to achieve this level of water
integrity all grommets must be occupied by round-section
cables of between 4.5mm and 10mm diameter.
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-4’s built-in rmware is held in “ash” memory,
allowing quick and easy upgrades using a simple Microsoft
Windows (98 SE/ME/NT/2000/XP) user interface program
(ActiPatch) running on a connected PC.
It is our policy to provide these updates free on our website,
www.actisense.com. This upgrade can be performed
with the unit completely in-situ, via a PC connected to the
Port 0 (OPTO IN 0 and ISO OUT 0) or the USB port.