NMEA Combiner / Multiplexer
Standard Model
The Brookhouse standard NMEA Combiner / Multiplexer combines NMEA 0183 data from up to four marine instruments ( NMEA-talkers ) into a single data-stream for input via a single computer port, or “ NMEA listener ”. A configurable fifth input port is available for receiving return data from a computer for auto pilot control or for connection of an AIS receiver.
The Brookhouse Multiplexer is an essential component for the integration of instrument/computer systems on board boats. Versatility, functions and price/performance are unmatched by any other comparable products.
All Brookhouse NMEA Multiplexers use the same micro-processor and well-proven software. The multiplexer NMEA input ports are opto-isolated and RS232, USB (optional) and RS422 output ports are available for the connection of computer, autopilot, repeaters and other NMEA listeners.
With AIS (Automatic Identification System) receivers now frequently used, the ability to combine standard low speed NMEA talkers and high-speed AIS in one data-stream has become an important requirement. The Brookhouse standard multiplexer models support connection of AIS receivers via a configurable (5th) input port. However, if besides AIS support, the multiplexer is also required to process return data from a computer or chart plotter, typically to feed an autopilot for steering to a waypoint or along a route, we recommend using one of the new Brookhouse multiplexer models with baudrate conversion (models AIS and AIS-C).
The standard model Brookhouse NMEA Multiplexer is very affordable, but loaded with useful features, including NMEA filtering and "on the fly" editing and including the "GPS backup switch" feature. Seatalk support is available as an option. In Seatalk-mode, channel 1 is connected to the Raymarine Seatalk bus. Data from Seatalk marine instruments is converted into standard NMEA format and is output via the RS232 and RS422 output ports together with NMEA data from other instruments, connected to the 3 other channels. In this mode, the Brookhouse Multiplexer is effectively both a NMEA multiplexer and Seatalk bridge. The Seatalk page contains detailed information about the Seatalk Option for Brookhouse NMEA Multiplexers.
The Brookhouse NMEA Multiplexer uses the latest microcontroller technology which requires a minimum of components. This makes the device reliable and low cost. Smart firmware to manage and buffer the NMEA data ensures high efficiency and data-integrity.
Operation of the unit is fully automatic. When power is switched on, it starts acquiring data and starts outputting the combined data via the output-ports.
Other Brookhouse NMEA multiplexer models are:
Model
NMUX-AIS
Model NMUX-AIS_C
Model NMUX-R
Why a NMEA Multiplexer?
Computer-aided navigation has come of age. Many discerning yachtsmen have recognised the advantages of using a computer on board for chartplotting and navigation. On smaller yachts this is often a laptop computer. There are many excellent programs available that can process a variety of data produced by a number of marine instruments and that offer a tremendous amount of useful navigational information in a user-friendly format, which makes navigation easier and safer. These programmes receive their ( NMEA ) input via a single COM-port. The most important for navigation is of course the data from the GPS receiver. However, on a modern yacht with modern electronics there are usually a number of different sources of NMEA - data, such as data from the speed-log, wind-instruments, electronic compass, depth sounder, AIS receiver, etc. To make optimal use of all this data in the computer, it is necessary to combine the NMEA data into one data-stream that can be input by the program via a designated COM - port. On most laptop computers the USB port will be used for this purpose (see below). After investing thousands of dollars in instruments it only makes sense to be able to access all data produced by these instruments at a central point, i.e. the board computer, where the benefits are at their maximum.
The NMEA combiner can also be used in configurations without a computer, for example if 2 or more NMEA sources need to be combined for input into an autopilot or repeater instrument. The availability of the NMEA combiner makes it no longer necessary that for compatibility all instruments have to be of the same product-range or the same manufacturer, as the standard NMEA format allows combining and mixing of different brands of instruments.
USB
Most of today's laptop computers have no RS232 port and only support USB. A USB interface is available for all Brookhouse NMEA multiplexers as a reasonably priced optional extra. The integral USB adapter allows direct connection of the NMEA Multiplexer to a USB 1.1 or 2.0 compliant port. Brookhouse multiplexers with the USB interface can still be connected via a serial RS232 port as well. A USB cable of 1.8m (6 ft) length is included as well as USB driver software for all Windows versions, incl. Vista.
Installation and Cabling
Installation is simple and can be carried out by anyone with a basic understanding of electrics. A clear diagram is included in the instructions and examples of integrated system wiring can be found under "diagrams" on this website. For connection of the instruments, follow the manufacturer's instructions. For connection of Raymarine Seatalk instruments, go to the Seatalk page.
4 opto-isolated “Listener” (Input) ports for the connection of NMEA "talkers" (GPS, Windinstr. etc.) or RS232 (Computer).
1 configurable RS232 input port for AIS receiver or computer return data, typically for Auto Pilot.
1 Output RS232 port (typically for connection to computer)
1 Output RS422 port (differential NMEA talker port)
Data
speed: 4 Input ports: 4800BPS (standard NMEA speed)
RS232 Output
port: 4800/9600/19200/38400 bps selectable in setup mode, default 4800 bps.
Indicators: red LED for power, green LED for data-transmission.
Supply Voltage: DC 9-35 Volts.
Reversed polarity protection.
Power Consumption: 45 mAmps. @ 12V (with all ports active)
Physical size: 110x65x37mm (hxwxd)
Weight: 120 grams
Mounting: bulkhead mounting with screws.
NMEA management and control:
NMEA Sentence Filtering
NMEA Sentence editing “on the fly”
Automatic port switching (mainly for GPS backup)
Data pacing for fast talking sensors and electronic compasses.
Options:
Raymarine Seatalk support
USB computer connection
User programmable LCD
Installation is
straight forward. From each NMEA device 2 wires have to be connected (+ and - or
A and B) to a NMEA IN port on the multiplexer. Also consult the user manual of
the instruments to be connected.
Connection of the multiplexer to a computer is via RS232 or USB or both.
Connection of an autopilot, a repeater instrument, Radar or any other NMEA
listeners is via the multiplexer's RS422 port (recommended NMEA) or the
RS232 output.
More technical information Brookhouse home
Note: Seatalk is a trade-mark of RayMarine.
