MiniPlex-BT - CustomWare

MiniPlex-BT NMEA-0183 multiplexer
MiniPlex-BT, V1.0
Firmware V2.9.4 122
© CustomWare, 2009
The MiniPlex-BT is a four-channel NMEA multiplexer, enabling the connection of multiple NMEA0183 instruments to each other and a computer. Available are four NMEA inputs (listener-ports),
two NMEA outputs (talker-ports), a serial port (RS-232) and a Bluetooth interface for a wireless
connection with a computer or PDA (Personal Digital Assistant, like Windows CE PDA’s or Palm
PDA’s). Connection of an AIS receiver or transponder communicating at 38400 baud is also
supported The multiplexer offers many features for manipulating incoming NMEA data like sentence
filtering, real time mode, talker ID modification and SeaTalk to NMEA translation in order to read
data from Raymarine instruments like the ST40, ST50 and ST60 series.
In 1
In 2
In 3
Out 2
The multiplexer reads NMEA sentences from the listener ports and stores them in a buffer, one for
each input. The sentences are read from the buffers in a round robin fashion - one sentence at a
time - giving each listener port equal priority. Each sentence is then sent to the talker port(s), the
Bluetooth interface and the RS-232 interface.
The speed of the listener ports is fixed to 4800 Baud (= bits per second), which equals 480
characters per second. When all listener ports receive data at this rate, the buffers will not be
emptied in time and an overflow situation occurs. The red LED indicates this situation. When a
buffer is full, a partially received sentence will be discarded, to ensure that the multiplexer only
sends complete and valid NMEA sentences.
There are several ways to resolve an overflow situation:
Configure the instruments on the listener ports to send less data or with greater intervals.
It is often possible to disable non-relevant sentences.
Many instruments do not allow selection of NMEA sentences to be output. In this case, use
the NMEA sentence filter in the multiplexer to block unwanted sentences. Unwanted
sentences are discarded immediately.
Set the operation mode of the multiplexer to Server mode (factory default). This mode
only sends incoming data to the computer/PDA and to NMEA Out1, which is high speed. In
Hub mode, the high-speed ports must wait for every character to be transmitted over the
low speed NMEA Out 2 port.
Increase the speed of the RS-232/Out1 port on the multiplexer. The maximum speed is
38400 Baud. From 19200 Baud and up (4 x 4800!) an overflow will never occur, except
when the multiplexer is set to Hub Mode.
The multiplexer has two talker ports, ‘Out 1’ and ‘Out 2’. All received sentences from the listener
ports are available on talker port ‘Out 1’. Talker port ‘Out 2’ can be configured to output either all
received sentences from the listener ports and the computer/PDA (Hub Mode), or only sentences
from the computer/PDA (Server Mode). See the table below.
NMEA Out 1
In 1
In 2
In 3
In 4
NMEA Out 2
Bluetooth Out
RS-232 Out
H: Hub mode, S: Server mode, A : AIS mode
NMEA Listener Ports
The multiplexer has four listener ports, ‘In 1’ to ‘In 4’. Each listener port should be connected to
one instrument only. These inputs are galvanically isolated from the multiplexer, as specified in the
NMEA-0183 standard.
Connect the ‘a’ and ‘b’ terminals of the listener port on the multiplexer to the ‘a’ and ‘b’ terminals
of the talker port on the instrument. Other designations used are for instance ‘Data +’ and ‘Data -’,
‘TX+’ and ‘TX-’ , ‘Out +’ and ‘Out –’ or ‘ve+’ and ‘ve-’.
Some instruments have single ended talker ports, with only one data terminal. Connect this
terminal to the ‘a’ terminal on the multiplexer, and connect the ‘b’ terminal on the multiplexer with
the ground of the instrument. The latter is often combined with the power supply ground.
Out A / +
In A
In A
Out B / -
In B
In B
NMEA Talker Ports
Both talker ports can be connected to up to four instruments. Connect the ‘a’ and ‘b’ terminals of
the talker port on the multiplexer to the ‘a’ and ‘b’ terminals of the listener port(s) on the
instrument(s). Other designations used are for instance ‘Data +’ and ‘Data -’, ‘TX+’ and ‘TX-’ , ‘Out
+’ and ‘Out –’ or ‘ve+’ and ‘ve-’.
Some instruments have single ended listener ports, with only one data terminal. Connect this
terminal to the ‘a’ terminal on the multiplexer, and leave the ‘b’ terminal on the multiplexer
unconnected. Connect the ‘Com’ terminal on the multiplexer with the instrument ground.
Out A
In A / +
Out A
Out B
In B / -
Out B
Out A
In A / +
In A / +
Out B
In B / -
In B / -
Multiple instruments
The shield terminals (Shld) can be connected to the screen/shield of the cable, if present. This
should always be done on one end of the cable only, preferable on the talker side.
SeaTalk® is a proprietary protocol developed by Raymarine®. This protocol is used for
communication between Raymarine navigation instruments like the ST40, ST50 and ST60 series.
To be able to use these instruments with commonly available navigation programs or to feed their
data into other non-Raymarine instruments, the SeaTalk data needs to be translated into NMEA.
Even Raymarine's own navigation software, Raytech Navigator, needs this translation.
The multiplexer can be connected to a SeaTalk network. It will translate all SeaTalk data required
for navigation into NMEA sentences. NMEA Input 4 can be switched to SeaTalk mode and should be
connected as follows:
SeaTalk cable
In 4A
In 4B
Connecting a SeaTalk network
The screen of the SeaTalk cable is not connected to the multiplexer.
The MiniPlex-BT communicates with a computer or PDA through its Bluetooth interface, allowing
the computer/PDA to receive all incoming NMEA data. The computer/PDA can also send data back
to the multiplexer, which can be used to control an autopilot connected to NMEA Out2.
The Bluetooth interface uses the ‘Serial Profile’, which means that on the computer/PDA, this
connection is presented as a standard COM port. Such a COM port can be opened by any
application. To setup a connection, the MiniPlex-BT must be paired to your computer/PDA. Pairing
is a process that makes a Bluetooth device known to a computer and vice versa, by their unique
address. Pairing is initiated on the computer or PDA by issuing the appropriate commands on the
respective devices. Mostly this will be something like ‘Find Bluetooth Devices’. This operation will
show a list of Bluetooth devices in the near surroundings that have responded to the
computer’s/PDA’s inquiry scan. The multiplexer will be listed as “MiniPlex BT”. Select the
MiniPlex BT entry and enter the required passkey when asked. The passkey of the multiplexer is
‘0000’ (four zeros). Follow the directions of your Bluetooth adapters’ software to finish the pairing
process and assigning it to a COM port (in case of a computer). This COM port will now be assigned
to the MiniPlex-BT.
Data that is sent over the Bluetooth connection to the multiplexer will appear at NMEA Out2 but
also at the RS-232 interface of the multiplexer when configured in Hub-mode.
RS-232 Serial Port
The RS-232 interface or serial port on the multiplexer can be connected directly with the serial port
of a computer, as shown in the diagram below.
rear-view of
9-pin sub-D connector
The RS-232 interface behaves in exactly the same way as the Bluetooth interface. All received
NMEA data is available on both the RS-232 and the Bluetooth interface. If data is sent to the RS232 interface in Hub-mode, it will not only be sent to the NMEA Out2 port, but also to the
Bluetooth interface.
This allows a PDA to be used as a wireless repeater for navigation information generated by the
software on the computer.
The RS-232 interface is set to 38400 baud when shipped. It can however be set to any speed in
the range from 4800 to 38400 baud using the MPX-Config utility. The RS-232 interface also
doubles as an AIS input/output when the multiplexer is set to AIS mode.
Power Supply
The multiplexer operates from a DC supply voltage from 8 to 35V and is protected against reversed
polarity. It is recommended to connect the multiplexer to the same power source or circuit breaker
as the ships instruments and/or computer.
Various options can be configured on the multiplexer, using the supplied configuration program
MPX-Config. There is no installation procedure for this utility, just start it from the CD or copy it to
a suitable folder on the hard disk of your computer. The top part of MPX-Config shows the NMEA
sentences that are received by the multiplexer. The bottom part shows the configuration controls.
The File menu allows you to store the configuration settings of the multiplexer to a file or load the
configuration from a file. This file format is similar to the Windows INI file format, allowing editing
the files with a text editor. See the Technical Reference section for an example of a configuration
The multiplexer is configured with proprietary NMEA sentences. MPX-Config sends these sentences
to the multiplexer but they can also be issued with a terminal program. See the Technical
Reference section for a complete reference of the supported proprietary sentences.
All configuration settings are stored in the multiplexer’s non-volatile memory. These settings are
retained without power supply.
Screenshot of MPX-Config
Serial Port
Before being able to configure the multiplexer, select the serial port to which the multiplexer is
connected or the serial port assigned by the Bluetooth pairing process. When selecting the baud
rate, either choose 38400 (factory default) of choose ‘Automatic’ to let MPX-Config detect the
communication speed of the multiplexer automatically. This may take a few seconds, especially
when instruments are sending data to the multiplexer. When a ‘Multiplexer does not respond’ message appears, disconnect or shut down the connected instruments. Another option is to try
every possible setting from 4800 to 38400 baud, until NMEA data appears in the top window of
MPX-Config. When the right baud rate has been found, the multiplexer will follow any change you
make: when you set MPX-Config to 38400 baud, the multiplexer will also be set to this value in
order to stay ‘synchronized’ with MPX-Config. If you exit MPX-Config, the settings will be saved.
Note that the Serial Port speed also affects the speed of NMEA Out1, since both ports run in
parallel. When accessing the multiplexer through the Bluetooth port, the baud rate setting does not
affect the speed at which the data is transferred between the computer/PDA and the multiplexer.
Read Configuration
Every time you start MPX-Config, it will request the current configuration from the multiplexer.
When this is unsuccessful (various controls on the MPX-Config window are greyed), you can
manually request the current configuration with this button.
The status line on the bottom of the MPX-Config window will show the name of the multiplexer, the
internal software version, the serial number and the optionally loaded configuration file.
Various options can be enabled on the multiplexer by checking one of the
checkboxes as shown on the right.
The Priority option assigns a priority to incoming NMEA data, based on
which input channel it is received. The RS-232 and Bluetooth inputs both
have the highest priority, followed by NMEA In 1, 2, 3 and 4 in descending
order. If for instance two GPS receivers are connected to input 1 and 2 and both GPS receivers
output GPRMC sentences, only the sentence from the GPS on input 1 is passed. This feature can be
useful to set up a second GPS as a backup for the main GPS.
The multiplexer only uses the sentence formatter (the ‘RMC’ part) for comparison. Another useful
application is when a Loran-C receiver is used as a backup for the GPS. With the GPS connected to
input 1 and the Loran-C receiver connected to input 2, the NMEA data from the GPS is passed while
similar NMEA sentences (e.g. LCRMB, LCGLL) from the Loran-C are blocked. When the GPS fails, a
timeout mechanism ensures that after 10 seconds the NMEA data from the Loran-C is passed
through the multiplexer.
Please note that not every sentence from a lower priority input is blocked. When for instance the
Loran-C outputs GLC sentences (which a GPS definitely does not), these are passed through the
multiplexer too. The priority mechanism only works on sentences with a similar formatter
(characters 3 to 5).
The following example shows what is passed and what not. The left
column in the table shows the sentences from a GPS and the right
column the sentences from a Loran-C. The sentences that are greyed
in the table are blocked by the priority mechanism. The table shows
that only the GLL and RMB sentences from the Loran-C are blocked. If
it is necessary to block the remaining sentences from the Loran-C, the
Sentence Filter can be used.
(In 1)
(In 2)
The priority mechanism can store up to 30 sentence types to
determine their priority. The list is scanned every second and entries older than 10 seconds are
removed. This ensures that sentence types on lower priority inputs are passed when their
counterparts on higher priority inputs are no longer received.
Channel Numbers
This option inserts channel number information in the NMEA stream that is output by the
multiplexer. Each NMEA sentence that is output on the RS-232 and Bluetooth interface is preceded
by a proprietary NMEA sentence ‘$PSMDCN’, to indicate on which NMEA input the following
sentence was received. The following example shows that the IIGGA sentence was received on
input 1, the GPGGA sentence on input 2, the IIGLL sentence on input 1 and the HEHDT sentence
on input 3.
This channel number information is used by our utility VirtualPlex-1 to send NMEA sentences from
a certain input port on the multiplexer to a specific virtual serial port.
In the example on the right,
VirtualPlex-1 is configured to create
a virtual serial port COM3, which is
assigned to input channel 2 on the
multiplexer. Applications that open
COM3 will thus only receive NMEA
sentences from input channel 2 on
the multiplexer.
This option changes an HDG
sentence (magnetic heading) into an
HDT sentence (true heading). If the
HDG sentence contains a magnetic
variation, it is used to calculate the
true heading from the magnetic heading in the HDG sentence, otherwise the magnetic heading is
just copied into the HDT sentence. This option can be used when a device like a Voyage Data
Recorder needs a true heading from a gyrocompass while only a fluxgate compass is available.
SeaTalk -> NMEA
To enable translation of SeaTalk® into NMEA, check this option. SeaTalk is a proprietary protocol
developed by Raymarine® and it is used for communication between Raymarine navigation
instruments like the ST40, ST50 and ST60 series. To be able to use these instruments with
commonly available navigation programs or to feed their data into other non-Raymarine
instruments, the SeaTalk data needs to be translated into NMEA. See the Technical Reference
section for an overview of the SeaTalk data that is translated into NMEA.
Mode of Operation
The multiplexer can operate in four different modes: Server, Hub,
Automatic and AIS. Basically, these modes determine which NMEA data
is available on NMEA Out2.
Server mode:
In this mode, the combination of computer and
multiplexer acts as an NMEA server. Incoming NMEA
data from NMEA In1 to In4 is sent to computer and
NMEA Out1. NMEA Out2 only outputs data received from
the computer.
Hub mode:
In Hub mode, the multiplexer acts as a hub where all NMEA data comes together
and is sent out again. All incoming NMEA data from NMEA In1 to In4 and the
computer is available on NMEA Out2.
This mode has one limitation: since the NMEA data is sent to multiple outputs on
the multiplexer, the total throughput is limited by the speed of the slowest output:
NMEA Out2, which is fixed to 4800 baud. This may cause buffer overflows.
Auto mode:
When Auto mode is selected, the multiplexer automatically switches between Huband Server mode, depending on the presence of computer generated data. When
the multiplexer receives NMEA data from the computer, it switches to Server mode.
When no data is received from the computer for more than 10 seconds, the
multiplexer will switch to Hub mode.
AIS mode:
This mode is used to connect an AIS receiver or transponder running at 38400
baud. The AIS receiver or transponder must be connected to the RS-232 interface
of the multiplexer while the computer must be using the Bluetooth interface to
connect to the multiplexer. The communication speed of the multiplexer must be
set to 38400 baud. The multiplexer will now send the data received from the RS232 interface to the Bluetooth channel and to NMEA Out1, unlike in Hub or Server
mode, where it is also sent to NMEA Out2. NMEA Out1 can be connected to an AIS
capable chart plotter. Data sent from the computer to the multiplexer over the
Bluetooth channel will also be sent to the RS-232 interface. The multiplexer thus
provides a bi-directional channel between the RS-232 and the Bluetooth
Auto mode is very useful when sailing alternately with our without a laptop. Consider a typical
setup as shown below:
In 1
In 2
In 3
Out 2
When the laptop is on board, it will receive all information from the instruments and the running
navigation software is able to calculate the course to steer and drive the autopilot accordingly.
Because the laptop is sending NMEA data, the multiplexer is in server mode and the autopilot will
therefore receive information from the laptop only.
When the laptop is not on board or not sending any data, the multiplexer switches to hub mode
and sends all data from the instruments directly to the autopilot. This way, the autopilot will
receive course information directly from the GPS.
NMEA Out1 is not affected by the mode setting. On this output, only NMEA data from the NMEA
inputs is available. Since this output is connected in parallel with the RS-232 interface, it will
operate at the same speed as the RS-232 interface. When the RS-232 interface is set to 38400
baud, NMEA Out1 will also run at 38400 baud.
The Real-Time option bypasses the buffer on a specific channel. In normal
operation, all incoming NMEA sentences are stored in a buffer, one for each channel,
which holds approximately 2 seconds of NMEA. In situations with heavy NMEA
traffic, these buffers can be filled up quite rapidly until an overflow occurs (read LED
blinks). Normally an overflow situation is not dangerous, it only means that every
now and then an incoming NMEA sentence is discarded because the buffer has no
room left to store the entire sentence.
However, when a fluxgate or gyrocompass is connected, which sends it’s heading 10 or 20 times
per second, the corresponding input buffer on the multiplexer is filled up constantly. Together with
NMEA data from other instruments, the total amount of data passing through the multiplexer gets
so high that almost all used inputs are in constant overflow, resulting in an unacceptable delay of
information of up to 20 seconds. This makes it impossible for an autopilot to steer on a compass
By enabling the Real-Time option on a channel that is connected to a compass, the buffer on that
channel is bypassed and the NMEA data from the compass is passed through the multiplexer
immediately. Some NMEA sentences will be discarded when the multiplexer is
servicing another channel, but this is far less of a problem than having a 20 second
delay in the heading information.
The overflow indicators on the MPX-Config screen can also be used to determine
which channel is causing the overflow. The LED corresponding to the compass
channel will be lit almost continuously. See the section Operation for ways to
prevent an overflow.
Talker ID
The multiplexer allows you to change the talker ID of incoming sentences. Enter
the desired talker ID in the edit box of the desired channel and press the Set
button to send the setting to the multiplexer. Pressing the Read Configuration
button will read the Talker ID settings from the multiplexer. To clear a talker ID,
simply clear the edit box(es) and press the Set button. Please note that any
combination of two characters can be used as talker ID, including spaces.
Therefore, make sure you clear the edit box and not fill it with spaces if you want
to clear a talker ID.
With the setting as shown on the right, any NMEA sentence received on input
channel 1 will get talker ID ‘II’. Thus a GPRMC sentence from a GPS will be
changed into IIRMC.
This feature can be useful when similar sensors are connected to the multiplexer and the software
must be able to distinguish between the data from these sensors. A catamaran for instance could
have a depth sensor in each hull, sending similar sentences to the navigation software.
Sentence Filter
The sentence filter is a powerful feature that allows you to specify exactly which NMEA sentence
may be received on any channel, including the Bluetooth interface. Up to 30 rules can be entered,
either manually or by capturing the NMEA sentences that are received by the multiplexer.
Each filter rule consists of the address field of an NMEA sentence (2 characters for the talker ID
and 3 characters for the sentence formatter like ‘GPRMC’) and an indicator for each channel (Inputs
1 to 4 and the PC). The indicator can be toggled between a pass sign ( ) and a block sign ( ) by
clicking on it. This determines whether that specific sentence will be passed or blocked by the
multiplexer. Wildcards are allowed too by using the ‘-’ character.
An Example
The first step is to fill the list with NMEA sentences to
be filtered. This can be done automatically by pressing
the ‘Capture’ button. All controls will be disabled during
capture and the ‘Capture’ button changes to ‘Stop’.
Leave the capture mode running for approximately 10
seconds. By that time, all connected instruments will
have sent NMEA sentences. Press ‘Stop’ to end capture
To make sure all sentences are captured properly, no
Talker ID’s may be specified for input channels 1 to 4.
After the capture process, the list may look like the
example on the right: the list shows received sentences
GLL and RMC on input 1 and HEHDT on input 2 (GLL
and RMC would have been preceded by GP but more on
that later).
If for instance the GGA and GLL sentences have to be blocked, simply click on the pass signs of
both sentences, to change them into a block sign. Pressing the Store button sends the list to the
multiplexer. Now the filter is operational.
As can be seen in the picture, the GLL and RMC sentences contain two dashes (‘--’) to indicate a
wildcard. This means that the first two characters are not used in the comparison with received
data. In this case, the filter processes anything that has a sentence formatter of GLL or RMC. When
a list is captured, you can click on a sentence with the cursor and edit the characters of that list
entry. Thus a captured sequence with ‘GPRMC’ and ‘GPGLL’ can be changed into ‘--RMC’ and
‘--GLL’. A useful purpose for wildcards is to block proprietary sentences from a device by entering
‘P----’ in the filter list. This will block any sentence that starts with a ‘P’.
The number in the last column is a divisor factor. By default, this number is 0, which means that
every occurrence of that sentence is passed. To lower the frequency of a sentence, a number
between 2 and 99 can be entered. For instance, if a fluxgate compass is sending 10 sentences per
second, and the multiplexer or a connected device is suffering from an overflow, you can enter a 5
in the divisor column. The effect is that every fifth sentence will be passed while all others are
blocked. This brings the sentence frequency down from 10 to 2 sentences per second.
Managing the list
The filter list is managed in MPX-Config and can be stored to or retrieved from the multiplexer.
Clicking on a traffic sign toggles it between a pass sign ( ) and a block sign ( ), which determines
whether that specific sentence will be passed or blocked on that channel. Each column represents
an input of the multiplexer, including the input from the computer (PC). The following management
functions are available:
Stores the filter list from MPX-Config into the multiplexer. Any existing filter rules in the
multiplexer are overwritten with the ones in the list.
Loads the filter list from the multiplexer into MPX-Config. The loaded filter rules are
added to any existing rules in the list. If you do not want this, clear the list by pressing
the Clear List button first.
Delete a filter rule from the list in MPX-Config. Select the filter rule to be deleted by
clicking on the formatter (e.g. ‘RMC’) and press the Delete button.
Enables the capture mode. The filter list will be filled automatically with the NMEA
sentences that are received by the multiplexer. For this function to work properly, it is
necessary that any ‘Talker ID’ and ‘Channel ID’ settings be cleared first. Otherwise, the
list will be filled with modified sentences instead of the originals.
Add a filter rule. Type the desired sentence address into the edit box left of the Add
button and press Add or the enter key. This will enter a new filter rule with all channels
blocked ( ). The input is case-insensitive; every entered sentence formatter will be
converted into uppercase. The input must contain 5 characters, including wildcards.
Clear List This button clears the filter list in MPX-Config (not the multiplexer!). To clear the list in
the multiplexer, press the Store button after clearing the list in MPX-Config.
Manual NMEA input
MPX-Config allows manual entry of NMEA
sentences for testing, configuration etc.
Type the desired NMEA sentence in the edit box
as shown on the right and press the Send
button or the enter key. Do not precede the
NMEA sentence with a ‘$’ as MPX-Config will do
this for you. The input is case sensitive, so whatever you type will be sent literally to the
multiplexer. Since all NMEA commands are uppercase, you have to enter them as uppercase.
The multiplexer has two LED’s. The green LED indicates the reception of valid NMEA data on the
listener ports or the Bluetooth interface. The LED only blinks on valid NMEA sentences that start
with a ‘$’ or ‘!’ and end with a LF character, thus indicating a proper connection and polarity of the
connected instrument. In case of a reverse polarity, the green LED will not blink.
The red LED indicates a buffer overflow, in case more data is coming in than can be transmitted.
See section “Operation” for options to resolve an overflow situation.
Both LED’s will blink once when the power is applied to the multiplexer. When the red LED stays lit,
a hardware error is found during execution of the self-test.
The multiplexer is not waterproof. It should be mounted at a dry place, like behind the instrument
panel, on a flat surface. Do not mount the multiplexer in a metal enclosure or behind a metal
panel, as this obstructs the radio waves used for the Bluetooth connection.
Technical Reference
MPX-Config Registry keys
The serial port settings of MPX-Config are stored in the Windows registry, using the following keys:
MPX-Config INI file format
The configuration file format of MPX-Config resembles the standard Windows INI file format. Below
is an example with has all possible options listed. The example corresponds with the settings
shown on the MPX-Config screenshot on page 5.
Channel Numbers=0
HDG Translation=0
RealTime Ch.1=0
RealTime Ch.2=0
RealTime Ch.3=0
RealTime Ch.4=0
Talker ID1=
Talker ID2=
Talker ID3=WI
Talker ID4=
Proprietary NMEA commands
The multiplexer supports some NMEA commands through proprietary NMEA sentences. They also
generate certain proprietary NMEA sentences in some modes of operation or as a response to
NMEA commands.
All commands have the following format:
Start of a proprietary command. Dictated by the NMEA standard.
ShipModul manufacturer’s mnemonic.
Two- or three-character command code.
For ease of manual configuration, the commands issued to the multiplexer do not require a
checksum. Sentences output by the multiplexer always contain a checksum. Sentences output by
the multiplexer always contain a checksum, denoted with *hh in the descriptions below.
Command reference
VER – Get Version
Retrieves version information from the multiplexer. The multiplexer responds with the following
version sentence:
software version number
product descriptor
serial number
multiplexer capabilities. This is a 4 digit, 16-bit field represented as a
hexadecimal number. Each bit identifies a capability of the multiplexer. The
following bits are defined:
2-0: Interface type, 0 = serial, 1 = USB, 2 = Bluetooth
AIS mode supported (BT models only)
15: 3rd generation multiplexer
CN - Channel Number indicator
This sentence precedes an NMEA sentence to indicate through which input channel the sentence
was received.
channel number 1,2,3 or 4.
Example: $PSMDCN,1*1A<CR><LF>
CF – Configuration
This sentence sets the configuration of the multiplexer. The same sentence is sent by the
multiplexer in response to a CFQ sentence.
Command: $PSMDCF,b,m,s,p,n,rrrr,h[*hh]<CR><LF>
b: baudrate selector:
4800 baud
9600 baud
19200 baud
38400 baud
toggle checksum mode
Server mode
Hub mode
Auto mode
AIS mode (BT models only)
s: Seatalk translation: 0
dump all unknown Seatalk datagrams (PSMDST,xx,xx,…)
dump all Seatalk datagrams
toggle generated wind sentence between VWR and MWV
m: mode selector:
p: Channel priority:
1 = on, 0 = off
n: Channel numbers:
1 = on, 0 = off
r: Real-time mode:
1 = on, 0 = off. Four digits, one digit per channel, numbered from 1 to 4
h: Heading translation: 1 = on, 0 = off
hh: optional checksum
When sending this command to the multiplexer, it is not necessary to specify every field when only
one configuration parameter has to be changed. Fields preceeding the one to be changed can be
left blank. Fields after the one to be changed may be omitted. When for example only the channel
priority must be changed, the command “$PSMDCF,,,,1” may be sent. The fields ‘b’, ‘m’ and ‘s’ are
left blank while the fields for ‘n’ and ‘rrrr’ are omitted.
The ‘s’ field will always return a 0 or 1 in response to a CFQ command.
1) Normally the multiplexer blocks sentences which contain a checksum error. Toggling the
checksum mode lets the multiplexer pass sentences with a checksum error unprocessed. The
response of the CFQ command shows in which mode the multiplexer is configured: when a
checksum is added, the multiplexer is in normal mode and blocks erroneous sentences. When
the CF response shows no checksum, the multiplexer passes erroneous sentences.
CFQ – Request current configuration
This sentence requests the current configuration settings from the multiplexer.
The multiplexer responds with a CF sentence. When the response contains a checksum, the
multiplexer is in normal mode and blocks erroneous sentences. When the CF response shows no
checksum, the multiplexer passes erroneous sentences.
FL – Filter
This sentence speficies a filter rule which is applied on every incoming NMEA sentence. Sentences
for which a rule is specified, will only be transferred if the input on which they are received
matches the input specified in the filter rule.
Filter rules are specified by the formatter part of the NMEA address field, for instance the “GPRMC”
part of a GPS “$GPRMC” sentence. For each filter rule, the inputs to be passed can be specified.
Sentences for which no rule exists are passed unrestricted.
Sentence formatter of the filter rule (e.g. “GPRMC”, “IIMWV”, etc). This field may
contain wildcard characters (‘-‘). For instance, “GP---” will apply to all sentences
starting with “GP”. Similarly, “--MWV” will apply to all sentences ending on “MWV”
regardless of the talker ID. One filter rule with all wildcards and all inputs blocked is
allowed to let the multiplexer block all sentences for which no rule exists. When an allwildcard rule is entered, the multiplexer will not accept subsequent filter rules.
Example: $PSMDFL,-----,00000<CR><LF>
Inputs to pass. Each ‘x’ represents an input to assign to this rule, numbered from 0 to
4, where input 0 is the computer interface (serial or USB) and 1 to 4 represent NMEA
inputs 1 to 4. A ‘1’ means to pass, a ‘0’ means to block. When all x’es are ‘1’, the filter
rule is removed.
Optional divisor factor (0..99). The frequency of a sentence is divided by this number
to reduce the number of sentences in time. If for instance a divisor of 6 is specified for
a sentence, only every 6th sentence is passed. This can be used to reduce the output of
a high-speed heading sensor.
Optional checksum
A FL sentence without any parameters will erase all rules.
Example: $PSMDFL,GPRMC,10011<CR><LF>
This sentence specifies a rule for all sentences which have the “GPRMC” sentence formatter. When
this rule is applied, only “GPRMC” sentences on inputs 0 (the computer), 3 and 4 are transferred.
An FL sentence with wildcards on all positions is discarded.
FLQ – Request filter list
This sentence requests the filter list from the multiplexer. The multiplexer responds by sending FL
sentences, one for each list entry. An empty FL sentence denotes the end of the list.
The sentences may not be dumped as one contiguous block. In case of heavy NMEA traffic, they
may be interspersed with other NMEA sentences.
ID – Talker ID
Enables a Talker ID to be set for a specific channel. If the talker ID is set for a specific channel, the
original talker ID in the sentences received on that channel is replaced by the specified one, before
sending the sentence to the computer.
Talker ID for channel
Talker ID for channel
Talker ID for channel
Talker ID for channel
optional checksum
An empty field clears the ID and disables the translation for that specific channel. Sending PSMDID
without any fields clears all translations.
IDQ – Request talker ID’s
Requests the Talker ID Translation settings. The multiplexer responds with an ID sentence.
OV – Overflow
In case of a buffer overflow (blinking red LED on the multiplexer), an overflow sentence is output,
to indicate on which input buffer the overflow occurred:
Binary field. The first four bits indicate on which input buffer the overflow occurred.
Translated Seatalk datagrams
When the Seatalk translation is enabled, the following datagrams are translated into NMEA
Depth below transducer
Wind angle, (10 and 11 combined)
Wind speed, (10 and 11 combined)
Speed through water
Trip mileage (21 and 22 combined)
Total mileage (21 and 22 combined)
Water temperature
Total and Trip mileage
Speed through water
Water temperature
Lattitude, value stored
Longitude, value stored
Speed over ground, value stored
Course over ground. RMC sentence is
generated from stored values from 5x
GMT time, value stored
Date, value stored
Lat/Long, values stored
Magnetic heading, including variation (99)
Magnetic variation, value stored
As appears from the table, not all datagrams result in an NMEA sentence. Some datagrams are
only used to retrieve a certain value to be combined into one NMEA sentence.
When the Seatalk translation is enabled with with option 2 (the ‘s’ parameter in the CF sentence is
2), unlisted datagrams are translated into a proprietary NMEA sentence with the following format:
aa,bb,cc,dd… represent the hexadecimal value of the bytes from the received Seatalk datagram.
Technical Specifications
Supply voltage:
Current consumption:
Input resistance:
Filter list size:
Priority list size:
NMEA Out1:
NMEA Out2:
Speed NMEA In:
Speed NMEA Out1/RS-232:
Speed Bluetooth:
Speed NMEA Out2:
Bluetooth range:
Bluetooth Device Name:
Bluetooth Pass Key (PIN):
Bluetooth transceiver:
8 – 30 VDC, protected against reversed polarity.
100 mA (150 mA max. with fully loaded talker ports and active
Bluetooth connection).
4 x NMEA-183/RS-422, galvanically isolated. 1 input can be set to
SeaTalk mode.
>800 Ohm.
1 x RS-232, 2 x NMEA-183/RS-422, 1 x Bluetooth
6 buffers of 800 characters (4 x NMEA, 1 x Bluetooth, 1 x RS232).
30 sentence types
30 sentence types
Combined data from NMEA inputs.
Combined data from NMEA, Bluetooth and RS-232 inputs (Hub
mode) or from Bluetooth and RS-232 inputs only (Server mode)
4800 Baud.
4800-38400 Baud (NMEA HS).
38400 Baud internal, any speed selectable on computer.
4800 Baud.
Overflow and Data.
100 meters / 300 feet.
“MiniPlex BT”
Type: TDK TRBLU20-00100, Class 1 device.
Canada: 1931-TDK-BTISM.
138 x 72 x 33 mm.
Flame retardant ABS.
Declaration of Conformity
Borgstee 27b
9403 TS Assen
The Netherlands
Tel.: +31 592 375700
Fax: +31 592 375550
Declare under our sole responsibility that the product
ShipModul MiniPlex-BT
to which this declaration relates is in conformity with the following specifications:
EN/IEC60945:2002 and EN/IEC61162-1:2000
EN300328 and EN301489
FCC Title 47 CFR, Part 15, FCC ID: PI4-TDK-BTISM
The product herewith complies with the requirements of the EMC Directive 89/336/EEC and carries
the CE-marking accordingly.
Assen, 1-11-2008
M. Sprang
This device complies with Part 15 of the FCC Rules. Operation is subject to the following conditions:
(1) This device may not cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause undesired operation.
ShipModul / CustomWare
Borgstee 27b
9403 TS Assen
The Netherlands
+31 592 375700
+31 592 375550
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