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MiniPlex-42USB
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The
MiniPlex-42USB is the ideal solution for computers and laptops without a serial port. The functionality of this NMEA multiplexer is the same as the MiniPlex-42. It features 4 galvanically isolated NMEA inputs, 2 NMEA outputs and one bi-directional USB interface.
The two NMEA outputs (talker ports) allow distribution of the NMEA data to up to eight instruments.
The MiniPlex-42USB can be connected directly to the USB port of the computer, without an additional Serial<>USB converter. The supplied driver creates a virtual COM port on the computer, allowing all existing navigation software to be used with this multiplexer. |
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The combination of the MiniPlex-42USB and it's virtual COM port driver is a dedicated NMEA solution, as opposed to a generic Serial<>USB converter. It therefore does not exhibit the well known problems of these generic converters like false detection of mice when the GPS is switched on or sudden drop-outs in the NMEA data stream. Any attempt of Windows to detect Plug & Play devices on our virtual COM port is blocked. The result is that the MiniPlex-42USB is a real trouble-free Plug & Play solution. Just plug in the USB cable, load the driver disk, a few clicks and you're up and running! |
Features
The MiniPlex-42USB has a
rich set of features and configuration
options, enabling the user to tackle almost
any NMEA bottleneck or interface problem.
The supplied Windows utility MPX-Config
allows full configuration of the multiplexer
and monitoring of NMEA data passing through
the multiplexer.
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SeaTalk®
conversion
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When the
SeaTalk -> NMEA option is
selected, NMEA In 4 becomes a SeaTalk®
compatible input, offering conversion
of the most common SeaTalk datagrams
on a RayMarine® network
into NMEA sentences.
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Operating modes
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Server:
Data received on the NMEA inputs is
sent to the computer. Data received
from the computer is sent to a NMEA
output.
Hub: All received data (on
the NMEA inputs and from the
computer) is sent to the NMEA output.
Auto: Automatic selection
between Server and Hub
mode. This is a useful feature for
people who have a GPS and an autopilot
connected to the multiplexer, and
sometimes wish to sail without taking
their laptop on board. When the laptop
is not connected, the multiplexer is
in Hub mode and crosstrack- and
waypoint information from the GPS is
directly sent to the autopilot. When
the laptop is connected and sending
data, the multiplexer automatically
switches to Server mode and the
autopilot will receive crosstrack- and
waypoint data from the laptop instead.
The Auto mode also serves as
an emergency backup: when the laptop
or computer crashes, the multiplexer
will fall back to Hub mode
after a time-out of 10 seconds. |
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NMEA Filter
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A
flexible NMEA filter can be configured
to pass or block specific sentences
from each input channel. This greatly
reduces the chance of an overflow and
the resulting loss of data. Many GPS
receivers for instance, transmit RMC,
GSV, GSA, GLL and GGA sentences every
second, accounting for 85% of the
available bandwidth of the NMEA
channel. By blocking unwanted or
unnecessary sentences, bandwidth is
preserved for other instruments.
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Real-Time
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Gyro- and
fluxgate compasses produce NMEA
sentences at a high rate (10
sentences/second or more). This can
lead to a buffer overflow in the
multiplexer. Although this overflow is
handled properly without data
corruption, it will lead to a delay of
NMEA sentences of up to 20 seconds in
extreme situations. This produces a
severe problem for autopilots, which
cannot make proper course corrections
when their heading feedback is delayed
for 20 seconds. The Real-Time option
prevents this delay by bypassing the
buffer of that specific channel and
forwarding the data immediately to the
multiplexers' NMEA output. As a
result, the heading is never delayed
more than 0.2 to 0.5 seconds,
depending on the amount of other NMEA
sentences passing through the
multiplexer.
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Heading conversion
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This
option converts a Magnetic Heading
sentence (HDG) into a True Heading
sentence (HDT). If the originating
magnetic heading sentence contains a
magnetic variation, it is used to
calculate the true heading before
conversion. This feature is useful for
certain equipment like VDR's which
need a true heading input, while the
only available heading source is a
fluxgate, delivering a magnetic
heading.
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Channel Priority
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With
Channel Priority enabled, similar NMEA
sentences on different inputs are only
passed from the input with the highest
priority. The RS-232 port has the
highest priority, followed by inputs 1
to 4, in descending order. When for
instance two GPS receivers are
connected to inputs 1 and 2, and both
transmit the same type of NMEA
sentences, only those received on
input 1 are passed. A time-out
function ensures that similar
sentences from the GPS at input 2 are
passed when the GPS at input 1 stops
sending these sentences.
Another example is where a GPS
provides an SOG to a windmeter, while
the latter repeats the sentences from
the GPS. When the GPS is connected to
input 1 of the muliplexer (high
priority) and the windmeter to input 2
(lower priority), the GPS sentences
coming from windmeter will be blocked
automatically while wind related
sentences are passed.
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Channel Number
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When this
feature is switched on, the
multiplexer will transmit a
proprietary NMEA sentence indicating
on which input channel the following
NMEA sentence is received.
VirtualPlex-1 uses this to route NMEA
sentences from specific inputs to
specific virtual COM ports (Channels
option).
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Channel ID
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The
Channel ID option changes the talker
ID of every incoming NMEA sentence in
"Mx" where 'x' is a number from 1 to
4, according to the input the sentence
was received on. Example: an incoming
GPRMC sentence on input 2 is changed
in M2RMC. This is useful to
distinguish between sentences from two
similar instruments.
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Talker ID substitution
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Talker ID
substitution changes the talker ID of
incoming sentences in a similar way as
the Channel ID option does, but now
the talker ID can be specified for
each input channel. This option is
useful for software or instruments
that expect a specific talker ID.
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Screenshot of MPX-Config.
Click to enlarge.
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Specifications: |
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Supply
voltage: |
5VDC
from the USB bus or 8-30VDC
external power. |
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Current
consumption: |
50mA (100mA
max. with fully loaded talker ports)
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Inputs:
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4 x
NMEA-183/RS-422, galvanically isolated
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Outputs:
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1 x USB, 2
x NMEA-183/RS-422 |
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Buffers:
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5 buffers
of 1000 characters (4 x NMEA, 1 x USB)
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Filter list
size: |
50 sentence
types |
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Priority
list size: |
50 sentence
types |
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Speed NMEA
in: |
4800 Baud
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Speed NMEA
out: |
4800, 9600,
19200 or 38400 Baud |
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Dimensions:
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138 x 62 x
30mm |
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