MiniPlex-2USB NMEA 0183 multiplexer Manual

MiniPlex-2USB NMEA 0183 multiplexer Manual
MiniPlex-2USB NMEA 0183 multiplexer
Manual
MiniPlex-2USB, V2.0
Firmware V3.00
Art.no.: 1121
Man. rev. B
© CustomWare, 2011
Introduction ....................................................................................................................3
Talkers and Listeners .....................................................................................................3
The Multiplexer .............................................................................................................3
The MiniPlex-2USB ........................................................................................................4
Connections ....................................................................................................................5
NMEA Signals ...............................................................................................................5
NMEA Listener Ports/Inputs.............................................................................................5
NMEA Talker Ports/Outputs .............................................................................................5
Combining Ports............................................................................................................6
SeaTalk .......................................................................................................................7
USB port......................................................................................................................7
Power Supply ...............................................................................................................7
Driver Installation ............................................................................................................8
Windows 7 Installation ...................................................................................................8
Windows 2000/Vista/XP Installation................................................................................ 13
Mac OS X Installation................................................................................................... 13
Data Throughput............................................................................................................ 14
Configuration ................................................................................................................ 16
Menu......................................................................................................................... 17
Controls..................................................................................................................... 18
Communication Port.................................................................................................. 18
Read Configuration ................................................................................................... 18
NMEA Input settings.................................................................................................. 18
NMEA Output setting ................................................................................................. 19
Options ................................................................................................................... 20
Mode of Operation .................................................................................................... 21
Sentence Filter ......................................................................................................... 22
Manual NMEA input ................................................................................................... 23
Firmware Update ........................................................................................................... 24
Indicators ..................................................................................................................... 24
Mounting ...................................................................................................................... 24
Technical Reference........................................................................................................ 25
Firmware Update Error messages................................................................................... 25
MPX-Config Registry keys ............................................................................................. 26
MPX-Config INI file format ............................................................................................ 26
Proprietary NMEA commands......................................................................................... 27
Proprietary sentence definitions ..................................................................................... 27
VER – Get Version..................................................................................................... 27
CN - Channel Number indicator ................................................................................... 27
CF – Configuration .................................................................................................... 28
CFQ – Request current configuration ............................................................................ 28
SP – Speed.............................................................................................................. 29
SPQ – Request Speed ................................................................................................ 29
FL – Filter................................................................................................................ 29
FLQ – Request filter list.............................................................................................. 29
ID – Talker ID .......................................................................................................... 30
IDQ – Request Talker ID’s .......................................................................................... 30
OV – Overflow.......................................................................................................... 30
RESET – Reset the multiplexer .................................................................................... 30
LDR – Loader message .............................................................................................. 30
Translated SeaTalk datagrams....................................................................................... 31
Technical Specifications................................................................................................... 32
Declaration of Conformity................................................................................................ 33
2
Introduction
The MiniPlex-2USB is an NMEA multiplexer that enables the connection of multiple NMEA 0183
instruments to each other and a computer. It is developed to solve a fundamental problem with the
NMEA 0183 standard.
The NMEA 0183 standard defines a communication protocol that enables navigation instruments to
exchange data with each other. A compass can send a bearing to a radar to enable a north-up
display, a GPS can send cross-track information to an autopilot in order to steer a programmed
course. The same GPS can also send information to the radar at the same time since the NMEA
0183 standard specifies that one device must be able to send data to up to four other devices.
NMEA data is made up of short text messages with a strict format called sentences and are humanreadable.
Talkers and Listeners
Communication using the NMEA 0183 protocol involves at least one
device that sends NMEA sentences and another device that receives
NMEA sentences. By convention, a sending device is called a talker while
a receiving device is called a listener. The picture on the right shows
such a minimal system: a gyrocompass sending heading sentences to a
radar.
Gyro
Radar
The NMEA 0183 standard specifies that a talker should have enough driving capability to talk to
four listeners. This is as easy to achieve as telling a story to an audience of up to four people. The
only requirement is to talk loud enough.
The picture left below shows such a situation.
PC
GPS
VHF
Depth
Plotter
GPS
Radar
Wind
AutoPilot
Compass
It gets complicated when several talkers must send data to one listener as shown in the picture on
the right. Unless that listener has multiple inputs, this is not possible without help. Simply
connecting talkers to one listener as shown is like four persons simultaneously telling you a
different story. You can’t make head or tail of it. In electronics terms: the outputs of the talkers will
effectively short-circuit each other and the sentences they transmit will be corrupted. This is where
a multiplexer offers the solution.
The Multiplexer
A multiplexer, sometimes called ‘combiner’, has multiple inputs, each acting as a single listener
connected to a talker. It can also have several outputs are able to talk to multiple listeners. A
clever piece of software inside the multiplexer reads the NMEA sentences that are received on the
listener ports simultaneously and stores them into queues. Another part of the software retrieves
the sentences from the queues, one at a time, and sends them to the outputs of the multiplexer.
This way, four incoming streams of sentences are combined into one single stream.
3
The picture below shows a typical setup with a multiplexer combining data from a wind instrument,
a compass and a GPS and forwarding this data to a laptop and an autopilot. In this example, the
multiplexer has two types of outputs: an NMEA talker port called ‘Out1’ and a USB port to connect
to a computer. The multiplexer sends the received NMEA sentences to both the laptop and the
autopilot at the same time.
The USB connection with the laptop is actually bi-directional: the laptop acts as a listener and a
talker at the same time. It receives NMEA sentences from the instruments to be processed by
navigation software that is running on the laptop. This software can also generate NMEA sentences
to control an autopilot. These sentences are sent to the multiplexer, which in turn sends them to
the autopilot. These sentences can be combined with the ones received from the other navigation
instruments.
Wind
In 1
Laptop
USB
Compass
In 2
GPS
In 3
Out 1
Multiplexer
Auto-pilot
The MiniPlex-2USB
The MiniPlex-2USB is a multiplexer with four NMEA inputs (listener-ports), two NMEA outputs
(talker-ports) and one USB port to connect to a computer. The multiplexer combines NMEA data
that is received on the listener ports In1 to In4 and sends this data to talker ports Out1 and Out2
and to the USB port. This USB port is also used to send data from a computer to the multiplexer to
be forwarded to Out1, as well as to send commands to configure the multiplexer.
Every NMEA input on the MiniPlex is galvanically isolated, sometimes called opto-isolation because
of the use of opto-couplers for isolation. An opto-coupler is a small device that transports
information by means of light instead of electricity.
A galvanically isolated input prevents unwanted currents to flow between instruments and the
multiplexer. These currents can damage equipment or interfere with radio signals and should
therefore be avoided. Galvanically isolated inputs are required by the NMEA standard.
The USB port of the MiniPlex is also galvanically isolated, which isolates the computer from the
navigation network and protects it against potential damage caused by ground loops or voltage
spikes.
Both NMEA outputs can drive up to four listeners each. They are slightly different from each other:
Out1 is meant to be connected to an autopilot and repeater displays while Out2 is more suitable
to deliver data to a chartplotter. This will be explained later.
Besides the basic functionality of combining NMEA data from multiple sources, the MiniPlex offers a
range of features to manage NMEA data like Sentence Filtering, Input Priority with automatic
switchover, testing of data integrity, Talker ID modification and SeaTalk® to NMEA translation.
The MiniPlex can seamlessly be integrated into an existing Raymarine SeaTalk network when
SeaTalk mode is enabled. This mode changes one NMEA listener port into a SeaTalk input. When
connected to a Raymarine SeaTalk network, the multiplexer will translate SeaTalk data into NMEA
sentences and combine these with NMEA sentences that are received on the other listener ports.
Only one SeaTalk input is needed since the SeaTalk bus is a single-cable system that connects all
instruments together through one single cable. SeaTalk to NMEA translation in the MiniPlex works
only one-way. No NMEA sentences are converted into SeaTalk, the multiplexer is just listens on the
SeaTalk bus.
4
Connections
NMEA Signals
Although the NMEA 0183 standard very clearly specifies the signal names, voltage levels and
connection methods, the reality is far from this ideal world.
The most important property of an NMEA port is that the connections or wires are labelled ‘A’ and
‘B’ and that it uses a differential signalling scheme. This means that data is transmitted on both
wires, but in ‘opposite direction’. Both wires are driven between 5V and 0V and opposite of each
other. This means when A is 5V, then B is 0V and vice versa. The advantage of this signalling
scheme is that it is very insensitive to electrical interference. NMEA ‘A’ and ‘B’ are often labelled as
NMEA ‘+’ and ‘-’ respectively. When connecting devices, simply connect NMEA ‘A’ to NMEA ‘A’ or
NMEA ‘+’ and NMEA ‘B’ to NMEA ‘B’ or NMEA ‘-’.
Things get complicated when manufacturers don’t follow the NMEA 0183 standard, which is very
often the case. Many devices have an NMEA port, which is really an RS-232 port. The only
resemblance with the NMEA standard is the format of the data transmitted. Electrically, they are an
entirely different world. The used signal names differ wildly and often lead to confusion. When a
device has a listener port with connections ‘Data In’ and ‘Data Return’ it is not clear whether this
input is galvanically isolated or ‘Data Return’ is simply another name for ‘Signal ground’
As opposed to the NMEA standard, many devices use a single-ended signalling scheme where data
is transmitted on one signal wire while a power/signal ground presents the return path for data.
Single ended devices often have connections named as TX and Gnd (transmit and ground) on the
talker port and RX and Gnd (receive and ground) on the listener port. Also used are Data Out, Data
In and Signal Ground. Mix these with ‘standard’ NMEA connections and confusion is imminent!
In general it is safe to connect a single ended talker port to a differential listener port. Connecting
a differential talker port to a single ended listener port however is less obvious. When NMEA ‘B’ of a
talker port is connected to the signal ground of a listener port, the ‘B’ signal is effectively shortcircuited to ground. A properly designed talker port can handle this abuse but it will result in fairly
high currents in long cables, which in turn leads to severe interference on SSB radios and possibly
on VHF radios too. In the worst case, the talker port will be destroyed.
To overcome this problem, the MiniPlex multiplexers provide a Com terminal on each talker port in
addition to the ‘A’ and ‘B’ terminals. This ‘Com’ terminal is similar to a signal ground. To connect a
talker port of the MiniPlex to a differential NMEA listener port, use the ‘A’ and ‘B’ terminals. Use the
‘A’ and ‘Com’ terminals to connect to a single-ended or RS-232 listener port.
NMEA Listener Ports/Inputs
The multiplexer has four listener ports, In 1 to In 4. Each listener port should be connected to one
instrument only. These inputs are completely floating and 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. These terminals may also be labelled as 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 ground of the instrument to the B
terminal on the multiplexer. The instrument’s data ground is often combined with its power supply
ground.
Out A / +
In A
TX
In A
Out B / -
In B
Ground
In B
Instrument
Multiplexer
Instrument
Differential
Multiplexer
Single-ended
NMEA Talker Ports/Outputs
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).
These terminals may also be labelled as Data+ and Data-, RX+ and RX- , Out+ and Out– or
ve+ and ve-.
5
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 ground of the instrument to the Com terminal on the multiplexer. The
instrument’s data ground is often combined with its power supply ground.
Out A
In A / +
Out A
RX
Out B
In B / -
Out B
Ground
Com
Com
Multiplexer
Instrument
Multiplexer
Differential
Instrument
Single-ended
Out A
In A / +
In A / +
RX
Out B
In B / -
In B / -
GND
Com
Multiplexer
Instrument
Instrument
Instrument
Multiple instruments
The shield terminals on the multiplexer (Shld) can be connected to the screen/shield of the cable if
available. This should always be done on one end of the cable only, preferably on the end that is
connected to a talker port.
Combining Ports
It is sometimes necessary to combine a listener and talker port of the multiplexer to connect to an
instrument. One of the most commonly used combinations is the connection of a GPS to the
multiplexer. While some GPS receivers have properly designed NMEA ports, many only have an
RS-232 port which is single ended with three terminals: TxD (data out), RxD (data in) and Ground.
The picture below shows how to connect such a GPS to the multiplexer.
TxD
In1A
Ground
In1B
RxD
Out1A
GPS
Out1B
Com
Multiplexer
Connecting a GPS with an RS-232
port
6
SeaTalk
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 MiniPlex can be directly connected to a SeaTalk network. It will translate all SeaTalk data
required for navigation into NMEA sentences. Input In 4 can be set to SeaTalk mode
(SeaTalk -> NMEA) and should be connected as shown below:
Red
SeaTalk cable
Yellow
In 4A
In 4B
Multiplexer
Connecting a SeaTalk network
Note that the red and yellow wires are used! The screen of the SeaTalk cable is not connected to
the multiplexer.
USB port
The USB port connects the multiplexer to a computer or a USB hub with the supplied cable. The
supplied driver provides a virtual COM port to allow navigation software to communicate with the
multiplexer. The USB port is bi-directional: the multiplexer sends NMEA data to the computer and
the computer can also send NMEA data back to the multiplexer. This data is available on
NMEA Out 1.
The USB port is galvanically isolated from the multiplexer to prevent ground loops and excessive
currents that could otherwise destroy the multiplexer or the USB port of the connected computer.
The USB connection supports flow control, which is needed when waypoints and routes are sent
from the computer to a GPS through the multiplexer. While normal NMEA sentences are sent at
regular intervals, waypoints and routes are sent ‘in one go’ without any pause between these NMEA
sentences. This fills up the queue in the multiplexer almost immediately after which the multiplexer
discards the remaining waypoints and routes. The GPS now only receives a few waypoints and
partial routes.
Flow control prevents this from happening. When the queue in the multiplexer is almost filled, the
multiplexer signals the computer to stop sending data. When the queue is sufficiently emptied, the
multiplexer signals the computer to continue. This requires a special setting in your navigation
software, which is mostly called ‘Flow Control’. This setting can mostly be found in the port settings
of your software. Set the Flow Control to Hardware or CTS/RTS. This Hardware flow control is
virtualized over the USB connection. Do not use Xon/Xoff flow controls since this uses special
characters instead of a (virtual) signal. These characters are not part of the NMEA standard and
therefore ignored by the multiplexer.
Power Supply
The multiplexer must be powered from an externally supplied DC voltage from 8 to 35V. The power
supply connection is protected against reversed polarity.
7
Driver Installation
To use the MiniPlex-2USB with your computer, a USB device driver needs to be installed. This
driver creates a virtual COM port, which can be opened with any navigation software just like any
other COM port. Drivers are supplied for Microsoft Windows (Windows 2000, Windows XP, Windows
Vista, Windows 7) and Apple’s Mac OS X.
Windows 7 Installation
Due to enhanced security measures in Windows 7, drivers are required to be digitally signed. When
a device is connected that has no digitally signed drivers, Windows 7 silently aborts the installation.
It is however possible to install the drivers anyway. Follow the procedure as described below to
manually install the MiniPlex drivers.
Connect the MiniPlex-2USB to the computer and ignore the warning ‘Device Driver software was
not successfully installed’.
Open Control Panel -> System and Security -> Device Manager.
In the Device Manager, there will be a ‘ShipModul MiniPlex-2USB’ listed under ‘Other Devices’ as
shown in the picture.
Right-click on the MiniPlex entry and choose ‘Update Driver Software...’ from the menu that
appears. This will open the following window:
8
Choose ‘Browse my computer for driver software’. In the following window, choose the location of
the driver and press ‘Next’.
9
When Windows has successfully installed the driver, the following window appears:
You can close this window.
The Device Manager will now list an USB Serial Port under Other Devices:
10
Right-click on the USB Serial Port entry and choose ‘Update Driver Software...’ from the menu that
appears. This will open the following Window:
Choose ‘Browse my computer for driver software’. In the following window, choose the location of
the driver and press ‘Next’.
11
When Windows has successfully installed the driver, the following window appears:
You can close this window.
The Device Manager will now list a ShipModul MiniPlex NMEA Multiplexer under Universal Serial Bus
controllers and a MiniPlex Serial Port (COMx) under Ports (COM & LPT).
12
Windows 2000/Vista/XP Installation
When the multiplexer is connected to a USB port for the first time, Windows will detect new
hardware and prompts you for a driver. Insert the supplied CD into the drive and follow the
instructions on your screen. Don’t let Windows search the Internet for updated drivers. When
asked to automatically search for drivers, answer no and choose the option to tell Windows where
to find the driver. The driver can be found on the supplied CD, in de folder ‘USB Driver’. This folder
contains subfolders with drivers for various operating systems.
Windows will warn you that the drivers are not digitally signed and can pose a threat to the
stability of Windows. Just ignore that warning and continue with the installation.
The installation on Windows is a two-step process. First, the driver for the multiplexer will be
installed. Next, Windows will detect a USB Serial device and will install a second driver. On
Windows XP systems, there can be a delay of up to 10 seconds between the installation of both
drivers, which sometimes leads to the conclusion that the installation is complete after the first
driver is installed which is not the case. On Windows Vista and Windows 2000 systems, there is
only very little delay.
When the installation is complete, a new virtual COM port will be created. This COM port is shown
in MPX-Config as COMx (vcp) where ‘x’ is a number. Select this port in your navigation software.
The ‘vcp’ extension as shown in MPX-Config will not be visible in your navigation software.
If necessary, the number of this COM port can be changed in the Windows Device Manager. Click
on the ‘+’ sign next to the entry marked as ‘Ports (COM & LPT)’. This will expand the entry to list
all available COM ports on your computer. The port for the multiplexer is listed as ‘MiniPlex Serial
Port (COMx)’ where ‘COMx’ is the name of the newly created serial port.
To change this port number, double click on the MiniPlex Serial Port (COMx) entry to open the
property page for this port. Next, select the Port Settings tab and click on the Advanced…
button. In the appearing window the used port number can be changed. Do not change any other
setting in this window.
It is possible to select a port number that is already present on the computer, like COM1. The
original COM1 port will then be disabled as long as the multiplexer is connected to the computer.
This feature allows the port number to be set in a low range from COM1 to COM4, to accommodate
software that only allows COM1 to COM4 to be selected.
More than one multiplexer can be connected at the same time. Every new unit will create a new
virtual COM port. The number of the COM port will always be assigned to the same multiplexer
regardless of the USB port being used.
Windows allows a maximum of 256 COM ports. However not all software may be able to select
COM ports numbered above COM9.
When installing updated drivers, uninstall the original drivers first with the
Add/Remove Programs icon in the Control Panel or use the Update Driver button on the
Driver page of the MiniPlex Serial Port property-page.
Mac OS X Installation
The OS X driver is available as a disk image file (.dmg) and can be found on the supplied CD in the
‘USB Driver’ folder. Run the installer by double clicking on the icon. Follow the instructions on the
screen and reboot the computer when asked.
When the computer has rebooted, plug in the multiplexer. Then open System Preferences and
select Network. You should now get the message ‘New Port Detected’. Click OK and select
Network Port Configurations from the ‘Show’ list. The new port will be listed as
MiniPlex-xxxxxxxx where ‘xxxxxxxx’ represents the serial number of the multiplexer. Enable the
port by checking the On box and clicking Apply Now. You can now exit Network and use the
multiplexer in your navigation software.
13
Data Throughput
Depending on the configuration of the multiplexer, NMEA sentences are sent to one or more talker
ports with different communication speeds. A situation could arise where more data is received
than can be transmitted because of the speed settings of the listener and talker ports. Such a
situation leads to an overflow of queues in the multiplexer. When an NMEA sentence is being
received while a queue is full, this sentence is discarded. Only complete NMEA sentences are stored
and forwarded. This event is indicated by the red LED, which will blink briefly when a sentence is
discarded.
The MiniPlex can be operated in two different modes called Server and Hub mode. These modes
determine the flow of NMEA data to Out1 and have a major impact on the data throughput. It is
therefore very important to understand the difference between these modes.
In Server mode, data received on the listener ports In1 to In4 is sent to the USB port while data
received on the USB port is sent to talker port Out1.
In Hub mode, data received on the listener ports In1 to In4 is sent the USB port and to talker
port Out1, combined with the data that is received on the USB port.
In1A
In1B
In1A
USB
In2A
In2B
In2A
Out1A
In2B
Out1B
In3A
In3B
Out1A
Out1B
Com
Com
In3A
Out2A
In3B
Out2B
In4A
USB
In1B
Out2A
Out2B
Com
Com
In4A
In4B
In4B
Data path Server mode
Data path Hub mode
The pictures above show the flow of NMEA data in both modes. As you can see in Server mode,
only a path exists from the USB port to Out1. In Hub mode, an extra path exists between the
inputs and Out1, indicated by the darker arrow in the middle. Out1 now outputs data that is
received on the USB port and on the NMEA inputs.
The path from the inputs to the USB port and Out2 is unaffected by the operating mode. These
ports always output data received on the inputs. Port Out2 can be used to send data to a
chartplotter.
This leads to the different purposes of Out1 and Out2: Out1 is mainly used to control an
autopilot. The autopilot needs steering information such as waypoint data, cross track error and
heading. This information can either come from a GPS connected to an input of the multiplexer
(Hub mode) or from a navigation program running on a computer connected to the USB port
(Server mode). When a computer controls the autopilot, there is no need to send data from the
inputs to the autopilot, possibly causing overflows because of the low speed of Out1 (4800 Baud).
Out2 on the other hand, is mainly used to send data to a chartplotter. Especially when an AIS
receiver or transponder is connected to the multiplexer, this output needs to be set to 38400 Baud.
Most chartplotters also support this high speed.
Now back to data throughput. The standard speed of an NMEA port is 4800 Baud or bits/second,
representing 480 characters per second. It is quite obvious that when four inputs receive data at
480 char/s and all of this data must be sent out again on an output with the same bandwidth of
480 char/s, a huge problem will arise. When the MiniPlex is set to Server mode, this problem is
quite easy to overcome: simply set the speed of Out2 to 19200 Baud (1920 char/s) or higher.
When Out2 is not used, set it to the highest speed. When it is connected to a chartplotter, try to
choose the highest speed the plotter will accept. In Hub mode however, the same data is also sent
to Out1, which usually operates at 4800 Baud to control an autopilot. There is our bottleneck
again!
14
However…
NMEA data tends to be sent in bursts. Some devices line depth sounders or wind instruments only
send one sentence per second while a GPS may send bursts of up to 13 sentences every two
seconds. While the average throughput over time may be low, an input might fill its queue quite
rapidly when a burst of sentences is received. The queues in the MiniPlex are quite large and may
contain up to 30 sentences of GPS data.
A couple of occasional blinks of the red LED over a period of a few seconds means that large bursts
of sentences are received and a queue is hitting its limit. Some sentences are discarded but most
of them will be passed without problems. Such a situation is totally acceptable and would mean
that for instance one depth, wind or position update is missed every few seconds.
A quite different situation may arise with some fluxgates or gyrocompasses. These devices may
send their heading sentences with a speed up to 40 sentences per second! Instead of queuing a
burst of sentences every one or two seconds, the multiplexer must queue a constant stream of
sentences possibly utilizing the maximum bandwidth of the multiplexer. Such a situation can lead
to a queue that is constantly filled up to its maximum size. This in turn results in heading data that
can be up to 20 seconds old when it is forwarded, which is totally unusable for any autopilot to
steer on. Enabling the Real Time option for this input can solve this specific problem. This option
bypasses the queue entirely. Only one sentence will be stored now and sent out when the time slot
for this input arrives. Outside its time slot, incoming sentences will be discarded. A lot of heading
sentences will be lost now but the ones that are passed, are passed almost immediately. Hence the
name ‘Real Time’.
When the red LED is blinking severely or stays on almost
continuously, it is advisable to investigate which instrument or
input leads to this overflow. The MPX-Config utility will show on
which input the overflow occurs by a blinking indicator in the
NMEA Input Settings section. Opening the Statistics window
from the Tools menu will give an insight about the amount of data
in a queue and whether it is filled constantly or occasionally.
Some general rules are applicable for reducing overflow situations.
A simple rule of thumb is that an overflow can never occur if the
speed of an output is equal or higher than the combined speeds of
all inputs. For example: if the multiplexer is in Server mode and
all four inputs are set to 4800 Baud, the minimum output speed
equals 4 x 4800 = 19200 Baud. This rule is only a hard rule when
the input bandwidth is fully utilized i.e. an instrument is sending
data continuously. This is hardly ever the case. As mentioned
earlier, NMEA data is often sent in bursts, resulting in a much
lower overall bandwidth. It could be perfectly feasible to have a
system with four instruments connected to the multiplexer, while
running all in- and outputs on 4800 Baud without a single
overflow.
There are several ways to resolve overflow situations:
1. Configure the instruments on the listener ports to send less data or with greater intervals.
GPS receivers can sometimes be configured for this.
2. Use the Sentence Filter of the multiplexer to block unwanted sentences. Unwanted
sentences are discarded immediately and do not occupy queue space or bandwidth.
3. For sentences that should not be blocked, setting a divisor in the Sentence Filter may lower
the rate. A gyro may be ‘throttled down’ to 10 sentences per second or even less. From the
GPS output, the rate of the sentences containing satellite information could be lowered to
once every 10 seconds instead of being output every time a position is output by the GPS.
4. Set the operation mode of the multiplexer to Server mode (factory default). This mode
only sends incoming data to the computer and to NMEA Out 2, which is factory set to high
speed (38400 Baud). In Hub mode, the high-speed ports must wait for every character to
be transmitted over any low speed ports.
5. Increase the speed of port Out 2 on the multiplexer, especially when this port is not used.
The maximum speed is 115200 Baud. From 19200 Baud and up (4 x 4800!) an overflow
will never occur, except when the multiplexer is set to Hub Mode.
15
Configuration
The multiplexer can be configured with a configuration program called MPX-Config. This program
can be found on the accompanying CD. There is no installation procedure for this program, just
start it from the CD or copy it to a suitable folder on the hard disk of your computer and start it
from there.
The multiplexer itself is configured with proprietary NMEA sentences. MPX-Config sends these
sentences to the multiplexer when you change a control on the screen.
All configuration settings are stored in the multiplexer’s non-volatile memory. These settings are
retained without power supply.
Screenshot of MPX-Config
The screen is divided into four sections from top to bottom: the menu, the data area, the control
area and the status bar. The menu basically controls the MPX-Config program. The data area
shows the NMEA sentences that are received from the multiplexer. These sentences include the
NMEA data received by the multiplexer on its inputs as well as status messages generated by the
multiplexer. The latter can be recognised fairly easy: they all start with ‘$PSMD’. The control area
contains controls that determine the operation and configuration of the multiplexer. The status bar
shows the name or type of multiplexer that is connected, its internal software (firmware) version
number and its serial number. This information is useful when you need technical support. Also
shown are the optionally loaded or saved configuration file and a line counter when you have
started a log file.
16
Menu
The menu contains two sub-menus: File and Tools. The File menu contains the following options
to choose from:
Start Log…
Start writing NMEA data to a log file. A log file is a plain text file and
can later be opened by any text editor to examine the data. A log file
can be a useful tool for diagnostic purposes and is often requested by
us for support. If you enter a new filename in the file dialog window, a
new log file is created. If you choose an existing file, this file will be
overwritten with new data. The Log counter on the status bar will show
the number of NMEA sentences that are currently written to the log file.
Timed Log…
Start writing to a log file with the addition of a time stamp at the
beginning of each NMEA sentence.
Stop Log
Stop writing NMEA data to the current log file and close that file.
Load Configuration…
Load a previously saved configuration file into the multiplexer. The
current configuration will be overwritten. A configuration file stores all
settings made with MPX-Config. See the Technical Reference section for
a description of this file format.
Save Configuration
Save the current configuration to a file. If a file was previously opened,
that file will be overwritten. If no file has been opened before, you will
be prompted for a file name. The name of the currently loaded
configuration file is shown on the status bar.
Save Configuration As… Save the current configuration to a new file.
Update Firmware…
Load new firmware into the multiplexer. From time to time, new
features are developed for the multiplexer or bugs are fixed. New
firmware image files will then be made available through our website.
These image files can be downloaded to your computer and loaded into
the multiplexer with this option. This option will only be visible when
your multiplexer supports firmware updates. This is the case from
firmware version 3.00 and up. Multiplexers containing lower firmware
versions need to be returned to our factory for an update.
Exit
This option exits MPX-Config.
The Tools menu contains the following options to choose from:
Clear Screen
Clear the data area on the screen. New sentences will be displayed
from the top.
No Scroll
Normally, incoming NMEA sentences are displayed from the top down
and when the bottom of the data area has been reached, all sentences
are scrolled up one line before the new one is show. When No Scroll is
activated, a list of incoming NMEA sentences will be displayed that will
be refreshed constantly when new similar sentences are received. A
scroll bar will appear when the list grows beyond the length of the data
area. This feature allows you to closely examine the types of sentences
that are received from the connected instruments. Any proprietary
NMEA sentences that are generated by the multiplexer are also listed.
The can be recognised by the firsts four characters, which are ‘$PSMD’.
Show Statistics
This option opens a new window that will be displayed on top of the
MPX-Config window. This window show bars that indicate how much
NMEA data is stored in the input queues. This is a useful option for
diagnosing data congestion and overflow situations as mentioned in
paragraph ‘Data Throughput’. A queue that is filled constantly can lead
to unacceptable delays in data transfer.
About
Show a window with version information.
17
Controls
The control area of the MPX-Config screen contains al the controls to configure the multiplexer.
When MPX-Config is started, it will retrieve the current settings from the multiplexer and set the
controls accordingly. If this query is unsuccessful, some controls will not be filled with values. This
could happen when the multiplexer was not powered up when MPX-Config was started.
Communication Port
Before being able to configure the multiplexer, select the
communication port to which the multiplexer is connected. The virtual
port created by the driver is marked with ‘(vcp)’. Since the speed
setting has no relevance to the speed of the virtual serial port, the
setting will show Automatic and will be disabled once the current
configuration has been retrieved from the multiplexer.
If you exit MPX-Config, the port setting will be saved on your computer.
Read Configuration
Clicking this button will request the current configuration settings from the
multiplexer. MPX-Config will do this automatically when started but the very
first time, when no port has been selected, you need to do this manually after
selecting the communication port.
When the wrong port is selected, MPX-Config will respond with a ‘Multiplexer does not respond’ message and all controls will be disabled (greyed).
The status line on the bottom of the MPX-Config window will show the name of the multiplexer, the
internal software (firmware) version and the serial number.
NMEA Input settings
This section allows you to set various options for
each of the inputs of the multiplexer. The
settings of each input are grouped together in a
horizontal section.
Speed
This sets the speed of each NMEA input in a
range from 4800 to 57600 Baud. 4800 Baud is
the standard speed for navigation equipment.
Some fluxgate or gyrocompasses operate at
9600 Baud to accommodate the higher
throughput of 20 headings per second or more.
AIS equipment operates at 38400 Baud.
If you change the speed of In4, the speed of
Out1 will be changed too. In 4 and Out 1 share the same communication port inside the
multiplexer and therefore always have the same speed. Out 1 is generally used to control an
autopilot and should be left at 4800 Baud for this purpose. The settings for In4 and Out1 are
disabled and fixed to 4800 Baud when SeaTalk -> NMEA translation is enabled.
Care should be taken when selecting other speeds than 4800 Baud with respect to possible queue
overflows. See paragraph ‘Data Throughput’ for more information.
Talker ID
The multiplexer allows you to change the Talker ID of incoming sentences. The Talker ID consists
of the first two characters of an NMEA sentence and determines which instrument (talker) the
sentence is originating from. Enter the desired Talker ID in the edit box of the desired input and
press the Enter to send the setting to the multiplexer. A Talker ID may consist only of upper case
characters and numbers.
When the Talker ID is changed, the background turns yellow to indicate that de modified Talker ID
has not yet been sent to the multiplexer. Pressing Enter will send all Talker ID’s to the multiplexer
and the background colour will return to white again. It is possible to change all Talker ID’s first
and press Enter after changing the last one. Starting at the Talker ID field of input 1, pressing the
Tab key will jump to the Talker ID of the next input.
Clicking the Read Configuration button will read the Talker ID settings from the multiplexer. Any
modified Talker ID’s that have not been sent to the multiplexer yet (yellow background) will revert
to their original values. To clear a Talker ID, simply clear the edit box(es) by selecting them with
the cursor and press the Del or Backspace key on your keyboard and finally press Enter. An empty
Talker ID setting will show two dashes.
With the setting as shown in the picture, any NMEA sentence received on input 3 will get Talker ID
‘WI’. A combined wind instrument may output a Talker ID of ‘II’ – meaning ‘Integrated
18
Instrument’. Some navigation programs may not accept this and require ‘WI’ as Talker ID for
weather instruments. With the setting as shown, an IIMWV sentence from a wind instrument will
be changed into WIMWV. NMEA sentences received on inputs 1, 2 and 4 remain unchanged.
Setting a Talker ID can also be useful when similar instruments are connected to the multiplexer
while the navigation software must be able to distinguish between the data from these
instruments. A catamaran for instance could have a depth sounder in each hull, sending similar
sentences to the navigation software. Setting the Talker ID for two inputs to ‘H1’ and ‘H2’
respectively allows the software to recognise both depth readings separately.
Real-Time
The Real-Time option bypasses the queue for a specific channel. During normal operation, all
incoming NMEA sentences are stored in a queue - one for each channel - that can hold several
seconds of NMEA data. In situations with heavy NMEA traffic, these queues can be filled up quite
rapidly until an overflow occurs. If this is the case, the red LED on the multiplexer will blink as well
as one or more of the OF indicators at the end of each input section. The Statistics window (menu
Tools  Show Statistics) will show a constant high for such a queue.
An occasional overflow does not pose an immediate problem; it only means that every now and
then an incoming NMEA sentence is discarded because there is no room left in the queue.
However, when a fluxgate or gyrocompass is connected, which sends its heading 10 or 20 times
per second, the corresponding input queue in 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 this queue will be in a constant overflow situation, resulting in an unacceptable delay
of information of up to 20 seconds. This makes it impossible for an autopilot to steer on a compass
heading.
The overflow indicators (OF) at the end of each input section show which input is causing the
overflow. The indicator corresponding to the compass channel will be lit almost continuously. By
enabling the Real-Time option for the input that is connected to the gyro or fluxgate compass, the
queue of that input is bypassed and the NMEA data from the compass is passed through the
multiplexer without delay. Some NMEA sentences will be discarded when the multiplexer is
servicing another input but this is far less of a problem than having a 20 second delay in the
heading information.
See the section ‘Data Throughput’ for other ways to prevent overflow situations with different
instruments
AIS (Input 1 only)
This option enables AIS mode for input 1, in order to connect an AIS receiver or transponder to the
multiplexer. It sets the speed of In 1 to 38400 Baud and it prevents data received on In 1 to be
sent to Out 1 when the multiplexer is in Hub or Auto mode.
It is very well possible to connect an AIS receiver or transponder to any input and set that input to
38400 Baud, but this requires the multiplexer to be set to Server mode to prevent the AIS data
from being sent to Out 1, the port that is generally used to control an autopilot at 4800 Baud.
SeaTalk -> NMEA (Input 4 only)
To receive SeaTalk® data from Raymarine® instruments and convert it into NMEA sentences, this
option must be enabled. SeaTalk is a proprietary protocol developed by Raymarine and it is used
for data exchange 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 non-Raymarine instruments, the SeaTalk data needs to be translated into
NMEA sentences. See the Technical Reference section for an overview of which SeaTalk data is
translated.
Selecting this option will automatically set In4 and Out1 to 4800 Baud and disable these controls.
NMEA Output setting
This section allows you to set the speed of both NMEA outputs Out1 and
Out2. When you change the speed of Out1, the speed of In4 will also
change. Out 1 is generally used to control an autopilot and should be
left at 4800 Baud for this purpose. The settings for Out1 and In4 are
disabled and fixed to 4800 Baud when SeaTalk -> NMEA translation is
enabled.
19
Options
Various options can be enabled and set on the multiplexer that control
the way NMEA data is treated.
Priority
This option deletes duplicate NMEA sentences received on multiple
inputs. When enabled, the multiplexer assigns a priority to incoming
NMEA data based on the input on which it is received. The USB port has
the highest priority, followed by NMEA In 1, In 2, In 3 and In 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
those from the GPS on input 1 are 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 - the Talker ID
(the ‘GP’ part) is ignored.
Another useful application of Priority is when a GPS and an AIS transponder are connected to the
multiplexer. An AIS transponder also outputs sentences from its internal GPS. A navigation
program now receives GPS data from two sources that might differ in position due to GPS
inaccuracy. This will lead to navigation errors. When the AIS transponder is connected to input 1
and the GPS to input 2, all the NMEA sentences from the AIS transponder is passed while duplicate
NMEA sentences (e.g. GPRMC) from the GPS are blocked. When the AIS transponder fails, GPRMC
sentences from the GPS will be passed again after an adjustable timeout.
Please note that the priority system does not block an entire input, it only blocks duplicate
sentences. Sentences received from the GPS that are not received on the AIS input are passed.
The following example shows what is passed and what not. The left column in the table shows
sentences from the AIS transponder on input 1 and the right column
sentences from the GPS on input 2. The sentence that is greyed in the
AIS
GPS
table is blocked by the priority system. The table shows that only the
(In 1)
(In 2)
RMC sentence from the GPS is blocked.
GPRMC
GPRMC
The priority feature can store up to 50 different sentence types to
AIVDM
GPGGA
determine their priority. A time out mechanism ensures that sentences
received on lower priority inputs are passed again after an adjustable
time out when their duplicates on higher priority inputs are no longer received.
Check GPS status
Normally, the priority system detects the absence of NMEA sentences. With Check GPS status
enabled, it detects invalid sentences, specifically from a GPS.
When a second GPS is connected as a backup to the first GPS, the first GPS must completely fail
(stop sending data) before sentences from the second GPS are passed. In a situation where the
first GPS no longer receives any signal from satellites (broken antenna, cable etc.), it will still
output NMEA sentences and the priority system will not fall back to the second GPS. When Check
GPS status is enabled, the multiplexer checks the Status field of GPS sentences. When the Status
field indicates ‘Invalid data’, the multiplexer will block these sentences, allowing the priority system
to time out and pass sentences from the second GPS. Sentences of which the Status flag is
checked are APB, GGA, GLL, RMA, RMB, RMC and XTE.
Time Out
This setting allows you to set the time it takes before sentences from a lower priority input are
passed.
SeaTalk
This sets the priority of the SeaTalk data. It can be either Highest (SeaTalk - In1 - In2 - In3) or
Lowest (In1 - In2 - In3 - SeaTalk).
Channel Numbers
This option inserts input number sentences in the NMEA stream that is output by the multiplexer.
Each NMEA sentence that is output on the USB port is preceded by the 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.
20
$PSMDCN,1*1A
$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*2E
$PSMDCN,2*19
$GPGGA,143357.999,5301.0061,N,00635.5479,E,1,06,1.9,90.0,M,,,,0000*39
$PSMDCN,1*1A
$IIGLL,5301.0061,N,00635.5479,E,143357.999,A*22
$PSMDCN,3*18
$HEHDT,67.0,T*1E
Channel numbers allow distinguishing between similar data from different instruments, like two
depth sounders on the same boat.
HDG -> HDT
This option converts an HDG or HDM 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. Otherwise the magnetic heading value is just copied. 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.
Mode of Operation
The multiplexer can operate in three different modes: Server, Hub and Auto
Hub/Server. Basically, these modes determine which NMEA data is available
on NMEA Out 1.
Server mode: In this mode, the combination of computer and multiplexer
acts as an NMEA server. Incoming NMEA data from NMEA In
1 to In 4 is sent to the computer and NMEA Out 2.
NMEA Out 1 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 In 1 to In 4 and from
the computer is available on NMEA Out 1.
Incoming NMEA data from NMEA In 1 to In 4 only is available on NMEA Out 1.
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.
This may cause queue overflows!
Auto mode:
When Auto Hub/Server mode is selected, the multiplexer automatically switches
between Hub and Server mode, depending on the presence of data on the
computer interface. 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.
Auto mode is very useful when sailing alternately with our without a laptop. Consider a typical setup as shown below:
Wind
In 1
Laptop
USB
Compass
In 2
GPS
In 3
Out 1
Multiplexer
Auto-pilot
When the laptop is connected, 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 operates in Server mode and the
autopilot on NMEA Out 1 will therefore receive information from the laptop only.
When the laptop is not connected or the navigation software is 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.
21
NMEA Out 2 is not affected by the mode setting. On this output, only NMEA data from the NMEA
inputs is available.
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 USB port. Up to 50 rules can be entered, either
manually or by capturing the NMEA sentences received by the multiplexer on its inputs.
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 a checkbox for each channel
(Inputs 1 to 4 and the PC). Wildcards are allowed in the sentence formatter by using the ‘-’
character. A wildcard will match any character. The checkboxes can be checked and unchecked by
clicking on them. This determines whether that specific sentence will be passed or blocked by the
multiplexer.
Whenever the multiplexer receives an NMEA sentence, the list of filter rules is traversed until a
match is found. The order of filter rules in the multiplexer is exactly the same as shown in
MPX-Config. When a match is found, the input on which the sentence was received is checked
against the input settings in this rule to determine whether the sentence may be passed or not.
When no match is found, the received sentence is passed. This means that all sentences for which
no rule exist, are passed through the multiplexer.
It is important to know that any Talker ID settings are applied to the NMEA sentences before
applying the Sentence Filter.
Example 1
The first step is to fill the list with NMEA
sentences to be filtered. This can be done
automatically by clicking on 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. Click on Stop to end the capture
mode.
After the capture process the list may look
like the example on the right. The list shows
four received sentences: ‘RMC’ on input 1,
‘HDT’ on input 2 and ‘MWV’ and ‘MTW’ on
input 3.
If you’re not interested in the water
temperature (‘MTW’), uncheck the checkbox
on that line. Clicking on the Store button sends the rule list to the multiplexer. Now the filter is
operational. Please note that editing of the rule list is performed on the list in MPX-Config on your
computer. After editing is complete, the rule list must be sent to the multiplexer by clicking on the
Store button. Clicking on the Read Configuration button re-reads the rule list into MPX-Config.
Example 2
In the following example, some edits are
made to the captured rule list of Example 1. A
few rules with wildcards are added, a divisor
factor is entered and the default operation of
passing everything that is not in the list is
changed to blocking everything that is not in
the list.
The second rule in the list now shows a 5 in
the Div column. This is a divisor factor that
lowers the rate of an incoming NMEA
sentence. In this example the ‘HDT’ sentence
rate is divided by 5. Only every fifth sentence
is passed by the multiplexer. If these
sentences came in at a rate of 20 sentences
per second, thy will leave the multiplexer at a
rate of only 4 sentences per second. Any
number from 2 to 99 can be entered.
Rule 4 shows no checkbox, meaning a full
22
block of the ‘MTW’ sentence for all inputs.
Rules 5 to 7 show a ‘GLL’, ‘GGA’ and ‘GSV’ entry preceded with wildcards ‘--’. 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, regardless of the Talker ID.
When a rule list is captured, you can click on a sentence formatter with the cursor and edit the
characters of that entry. Thus a captured rule 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 rule list. This will block any sentence that starts with a ‘P’.
As mentioned earlier, all sentences are passed for which no rule exists. It can be desired however
to reverse this operation: block all sentences for which no rule exists. This can be achieved by
adding an ‘all wildcard’ entry consisting of 5 dashes (‘-----’) to the end of the list with all inputs
blocked. This entry acts as a ‘catch-all’ rule. When no match is found in the list, this last rule will
always match any sentence and causes it to be blocked. This entry must be the last entry in the
list. The multiplexer will not accept any rules after it has received an all wildcard rule.
Managing the list
The rule list is managed in MPX-Config and can be stored to or retrieved from the multiplexer.
Clicking on a checkbox changes its state from checked to unchecked and vice versa. This
determines whether a sentence is passed (checked) or blocked (unchecked). The following
management functions are available:
Store
Stores the rule list from MPX-Config into the multiplexer. Any existing filter rules in the
multiplexer are overwritten with the rules in the list.
Capture
Enables capture mode. The rule list will be filled automatically with the NMEA sentences
that are received by the multiplexer.
Add
Add a filter rule. Type the desired sentence address into the edit box above the Add
button and click on Add or press the enter key. This will enter a new filter rule with all
channels blocked. The input is case-insensitive; every entered sentence address will be
converted into uppercase. The input must contain 5 characters, including wildcards.
Numbers are also allowed.
Delete
Delete a rule from the list in MPX-Config. Select the entry to be deleted by clicking on
the address in the Sentence column (‘--GLL’ in the example) and click on the Delete
button.
Clear List This button clears the rule list in MPX-Config (not the multiplexer!). To clear the list in
the multiplexer, click on the Store button after clearing the list in MPX-Config.
A sentence address or divisor can be edited by first selecting it with the cursor. Entering Edit mode
can be done in different ways:
●
Press function key ‘F2’. This enters Edit mode with the cursor at the end of the text. Move the
cursor around with the mouse or arrow keys.
●
Press Enter or click with the cursor: This enters Edit mode with the text selected and the cursor
at the end. Any character or number that is typed now will erase the existing text entirely
unless the cursor is moved around with the mouse or arrow keys. This will unselect the text.
When changes are made, press Enter to confirm them or press Escape to discard any changes and
exit Edit mode.
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 click on the Send button or press the
enter key.
Preceding the NMEA sentence with a ‘$’ is optional. MPX-Config will add a ‘$’ if necessary. The input
is case sensitive, so whatever you type will be sent literally to the multiplexer. Since all NMEA
commands are uppercase, you have to enter them as uppercase.
Any sentence starting with ‘$PSMD’ will be recognized by the multiplexer as a configuration
command and will be processed as such. Any other sentence will be sent to NMEA Out1.
23
Firmware Update
From time to time, we will develop new features for the multiplexer or fix bugs in the existing
firmware. New firmware image files will then be made available through our website. These image
files can be downloaded to your computer and loaded into the multiplexer with the option Update
Firmware from the File menu.
In order to perform an update, download a firmware image file from our website
www.shipmodul.com and store it on your computer. Connect your computer to the USB port of the
MiniPlex.
Choose Update Firmware from the File menu.
A file dialog opens which allows you to select the previously downloaded image file ending at an
‘.mpx’ extension. When you have selected the file and clicked on OK, the update process is started.
The image file’s integrity and version is checked first before initiating the download procedure in
the multiplexer.
When the download is started, the red LED on the multiplexer will be lit continuously while the
green LED blinks on reception of data from the computer. MPX-Config will show a progress
indicator on the status bar during the update process. When the update is complete and successful,
a message will show ‘The firmware update was successful’.
Any errors that occur during the process will be shown. It is important to make a note of the error
message when asking for support. See the Technical Reference section for an explanation of the
error messages.
Indicators
The multiplexer has two LED’s. The green LED indicates the reception of valid NMEA data on the
listener ports or the USB port. The LED only blinks on valid NMEA sentences that start with a ‘$’ or
‘!’ and end with a CR and LF character, thus indicating a proper connection and polarity of the
connected instrument. In case of a reverse polarity of a connected talker, the green LED will not
blink.
The red LED indicates a queue overflow, in case more data is coming in than can be transmitted.
See section ‘Data Throughput’ for options to resolve this situation.
During a firmware update, the red LED will be on continuously when the update is in progress while
the green LED blinks on the reception of a data packet from the computer. This will give a visual
indication of the update process.
Mounting
The multiplexer is not waterproof. It should be mounted at a dry place, like behind the instrument
panel, on a flat surface.
24
Technical Reference
Firmware Update Error messages
During a firmware update, the following warnings or error messages may be displayed:
Before updating firmware, the speed of the Communication Port must be set to 115200
Baud
Updating firmware is done at a speed of 115200 Baud. If you would start the update while
operating at a different baudrate, MPX-Config would not be able to continue communicating
with the multiplexer after initiating the update process.
The firmware update failed
This message appears when the overall update process failed without any other error message.
It is shown when the updated multiplexer firmware does not report a version message after
start-up.
Not a valid firmware file
The file you are trying to open is not a valid firmware file. A firmware file not only ends with an
‘.mpx’ extension, it also contains a distinct signature that must be present. This prevents you
from accidentally loading the wrong file into the multiplexer.
Unsupported firmware file version
The firmware file version is not supported by MPX-Config. Currently, there is only one firmware
file version but it is not unlikely that in the future new version are developed which require an
update of MPX-Config.
Firmware file is corrupt
The firmware file is damaged, possible due to an error during download from our website.
The version of the firmware file is lower than the version of the multiplexer. Do you
really want to proceed?
You are trying to update the firmware in the multiplexer with an older version. This is just a
warning and very well possible to do.
Bootloader initialisation failed
When MPX-Config starts the update process, a small program called the Bootloader must be
started in the multiplexer. This message tells you that the bootloader could not be started. This
can happen when you try to update the multiplexer while navigation instruments are connected
and sending lots of NMEA data to the multiplexer. This can interfere with starting the update
process. Disconnect or power down the instruments to prevent this problem.
Firmware file does not match with the multiplexer type
Most firmware files will be compatible with all types of multiplexers. It is however possible that
special firmware is made available that only runs on a specific type of multiplexer. If this
message appears, you apparently are trying to update using a firmware file that is not suitable
for your type of multiplexer.
Bootloader: Erase command timeout
An error occurred when the bootloader tried to erase the old firmware.
Bootloader: Encryption command timeout
The bootloader did not respond to the Encryption command sent by MPX-Config.
Bootloader: Programming timeout
There was an error during programming a section of the firmware image.
Bootloader: CRC command timeout
The bootloader failed to calculate the checksum of the newly loaded firmware image.
Bootloader: CRC error
The calculated checksum of the newly loader firmware image does not match the checksum if
the image file. Apparently there was a communication error between MPX-Config and the
multiplexer. You can try to update again.
Invalid response from bootloader
The bootloader returned an unknown response to a command from MPX-Config.
25
MPX-Config Registry keys
The communication port settings of MPX-Config are stored in the Windows registry, using the
following keys:
HKEY_CURRENT_USER\Software\CustomWare\MPXConfig\BaudRate
HKEY_CURRENT_USER\Software\CustomWare\MPXConfig\SerialPort
MPX-Config INI file format
The configuration file format of MPX-Config resembles the standard Windows INI file format and is
readable text. Below is an example of the configuration file. This example corresponds with the
settings shown on the MPX-Config screenshot on page 6.
[Configuration]
Baud In1=1
Baud In2=0
Baud In3=0
Baud In4/Out1=0
Baud Out2=3
Mode=0
SeaTalk=1
Priority=1
Priority Timeout=3
Channel Numbers=0
RealTime Ch.1=0
RealTime Ch.2=1
RealTime Ch.3=0
RealTime Ch.4=0
HDG Translation=0
AIS Mode=1
Talker ID1=
Talker ID2=
Talker ID3=WI
Talker ID4=
[Filter]
GPRMC=01000,
HCHDT=00100,5
IIMWV=00010,
IIMTW=00010,
--GLL=00000,
--GGA=00000,
--GSV=00000,
26
Proprietary NMEA commands
The MiniPlex multiplexers are configured with 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:
$PSMDxx
$P:
SMD:
xx:
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, denoted with *hh in
the descriptions below.
Proprietary sentence definitions
VER – Get Version
Retrieves version information from the multiplexer. The multiplexer responds with the following
version sentence:
$PSMDVER,3.00,MiniPlex-2USB,10025943,8041*hh<CR><LF>
3.00:
MiniPlex-2USB:
10025943:
firmware version number
product descriptor
serial number
8041: 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:
1-0:
Interface type, 0 = serial, 1 = USB, 2 = Ethernet
2:
Bluetooth module installed
6:
Firmware update supported
15:
3rd generation multiplexer
hh:
checksum
CN - Channel Number indicator
This sentence precedes an NMEA sentence to indicate through which input channel the sentence
was received.
$PSMDCN,x*hh<CR><LF>
x:
channel number 1,2,3 or 4.
hh:
checksum
Example: $PSMDCN,1*1A<CR><LF>
27
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: $PSMDCF,b,m,s,p,n,rrrr,h,a,t[*hh]<CR><LF>
b: baudrate selector:
1)
m: mode selector:
0
1
2
3
4
5
9
=
=
=
=
=
=
=
4800 Baud
9600 Baud
19200 Baud
38400 Baud
57600 Baud
115200 Baud
toggle checksum mode
2)
0 = Server mode
1 = Hub mode
2 = Auto mode
s: SeaTalk translation: 0
1
2
3
4
=
=
=
=
=
off
on
dump all unknown SeaTalk datagrams (PSMDST,xx,xx,…)
dump all SeaTalk datagrams
toggle generated wind sentence between VWR and MWV
p: Channel priority:
=
=
=
=
=
off
on,
on,
on,
on,
n: Channel numbers:
0
1
3
5
7
standard priority order.
SeaTalk has highest priority.
standard priority order, GPS status checked
SeaTalk has highest priority, GPS status checked
1 = on, 0 = off
rrrr: Real-time mode: 1 = on, 0 = off. Four digits, one digit per channel, numbered from 1 to 4
h: Heading translation: 1 = on, 0 = off
a: AIS mode:
1 = on, 0 = off
t: Priority Timeout
0
1
2
3
4
5
=
=
=
=
=
=
3)
1 sec.
2 sec.
3 sec.
5 sec.
10 sec.
30 sec.
hh: optional checksum
When sending this command to the multiplexer, it is not necessary to specify every field when only
one configuration parameter has to be changed. Fields preceding the one to be changed can be left
blank. Fields after the one to be changed may be omitted. When for example only the channel
priority must be changed, the command “$PSMDCF,,,,1” may be sent. The fields ‘b’, ‘m’ and ‘s’ are
left blank while the fields for ‘n’, ‘rrrr’, ‘h’, ‘a’ and ‘t’ are omitted.
The ‘s’ field will always return a 0 or 1 in response to a CFQ command.
1) The speed setting is ignored on multiplexers without RS-232 serial port.
2) Normally the multiplexer blocks sentences that have 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 to the CF response, the multiplexer is in normal mode and blocks erroneous sentences.
When the CF response shows no checksum, the multiplexer passes erroneous sentences.
Note that this is a toggle, it does not change the baudrate and a CF response will always show
the normal baudrate setting (No. 0..3).
3) In AIS mode, Input 1 is not routed to Out1 when in Hub mode.
CFQ – Request current configuration
This sentence requests the current configuration settings from the multiplexer.
$PSMDCFQ<CR><LF>
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.
28
SP – Speed
This sentence sets the baudrate of the NMEA inputs and outputs.
$PSMDSP,a,b,c,d,e[*hh]<CR><LF>
The following fields are defined for setting the various ports:
a:
b:
c:
d:
e:
NMEA
NMEA
NMEA
NMEA
NMEA
In 1
In 2
In 3
In 4/Out 1
Out 2
These fields accept the following values:
0
1
2
3
4
=
=
=
=
=
4800 Baud
9600 Baud
19200 Baud
38400 Baud
57600 Baud (field <e> only)
Field <d> is ignored when SeaTalk translation is enabled with the $PSMDCF command.
SPQ – Request Speed
Request the baudrate settings of the NMEA inputs and outputs.
$PSMDSPQ<CR><LF>
The multiplexer responds with a $PSDMSP sentence.
FL – Filter
This sentence specifies a filter rule, which is applied on every incoming NMEA sentence. Sentences
for which a rule is specified, will only be transferred if the input on which they are received
matches the input specified in the filter rule.
Filter rules are specified by the formatter part of the NMEA address field, for instance the ‘GPRMC’
part of a GPS ‘$GPRMC’ sentence. For each filter rule, the inputs to be passed can be specified.
Sentences for which no rule exists are passed unrestricted.
$PSMDFL,ccccc,xxxxx,[dd][*hh]<CR><LF>
ccccc: 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 all-wildcard rule is entered, the
multiplexer will not accept subsequent filter rules.
Example: $PSMDFL,-----,00000<CR><LF>
xxxxx: 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 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.
dd:
Optional divisor factor (0..99). This number divides the frequency of a sentence over 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.
hh:
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 that have the ‘GPRMC’ sentence formatter. When
this rule is applied, only ‘GPRMC’ sentences on inputs 0 (the computer), 3 and 4 are passed.
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.
Example:
$PSMDFL,GPRMC,10011,0*hh<CR><LF>
$PSMDFL,GPGGA,10001,0*hh<CR><LF>
$PSMDFL,--VWT,01000,5*hh<CR><LF>
$PSMDFL,GPGSV,00001*hh<CR><LF>
$PSMDFL,*hh<CR><LF>
29
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.
$PSMDID,aa,bb,cc,dd[*hh]<CR><LF>
aa:
bb:
cc:
dd:
hh:
Talker ID for channel
Talker ID for channel
Talker ID for channel
Talker ID for channel
optional checksum
1
2
3
4
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 queue overflow (blinking red LED on the multiplexer), an overflow sentence is output,
to indicate on which input queue the overflow occurred:
$PSMDOV,x<CR><LF>
x:
Binary field. The first four bits indicate on which input queue the overflow occurred.
RESET – Reset the multiplexer
This command resets the multiplexer and starts the bootloader.
LDR – Loader message
This message is output by the bootloader. It contains the loader version and multiplexer ID. The
loader will wait for a special key during 0.2s after sending this message. When no key is received,
the application code is started. If no application code is found, the loader will continue sending this
message.
30
Translated SeaTalk datagrams
When the SeaTalk translation is enabled, the following datagrams are translated into NMEA
sentences:
SeaTalk
00
10
11
20
21
22
23
25
26
27
50
51
52
53
NMEA
DBT
MWV
MWV
VHW
VLW
VLW
MTW
VLW
VHW
MTW
------RMC
54
56
58
89
99
------HDG
---
Description
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
Latitude, value stored
Longitude, value stored
Speed over ground, value stored
Course over ground. RMC sentence is
generated from stored values from 5x
datagrams.
GMT time, value stored
Date, value stored
Lat/Long, values stored
Magnetic heading, including variation (99)
Magnetic variation, value stored
The table shows that not all datagrams result in an NMEA sentence. Some datagrams are only used
to retrieve data, which is combined with data from other datagrams to be able to form one NMEA
sentence.
When the SeaTalk translation is enabled 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:
$PSMDST,aa,bb,cc,dd…*hh<CR><LF>
aa,bb,cc,dd… represent the hexadecimal value of the bytes from the received SeaTalk datagram.
31
Technical Specifications
Supply voltage:
8 – 35 VDC, protected against reversed polarity.
Current consumption:
50 mA (100 mA max. with fully loaded talker ports).
Computer interface:
USB, galvanically isolated.
Inputs:
4 x NMEA 0183/RS-422, galvanically isolated. Input 4 can be set
to SeaTalk mode.
Input resistance:
>800 Ohm.
Outputs:
2 x NMEA 0183/RS-422.
Queues:
5 queues of 1024 characters (4 x NMEA, 1 x USB).
Filter list size:
50 sentence types
Priority list size:
50 sentence types
NMEA Out 1:
Combined data from NMEA inputs and USB port (Hub mode) or
from USB port only (Server mode).
NMEA Out 2:
Combined data from NMEA inputs.
Speed NMEA In 1-3:
4800 - 57600 Baud.
Speed NMEA In 4/Out 1:
4800 - 57600 Baud.
Speed NMEA Out 2:
4800 - 115200 Baud.
Indicators:
Overflow and Data.
Dimensions:
138 x 72 x 33 mm.
Housing:
Flame retardant ABS.
32
Declaration of Conformity
We,
CustomWare
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-2USB
to which this declaration relates is in conformity with the following specifications:
EN/IEC61000-6-1:1997 and EN/IEC61000-6-3:1996
EN/IEC61162-1:2000
FCC Title 47 CFR, Part 15 Class B
The product herewith complies with the requirements of the EMC Directive 89/336/EEC and carries
the CE-marking accordingly.
Assen, 1-1-2011
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.
33
ShipModul / CustomWare
Borgstee 27b
9403 TS Assen
The Netherlands
Tel.:
Fax:
+31 592 375700
+31 592 375550
web: www.shipmodul.com
e-mail: mail@shipmodul.com
34
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising