AISC
Installation instructions for Brookhouse NMEA multiplexer model AISC
General
This addendum describes connections and features of multiplexer model AISC where they are
different from the standard Brookhouse NMEA 0183 multiplexer. Please use the comprehensive
manual for the standard model for descriptions of general subjects such as the setup procedure,
USB connections, the optional LCD, backup switching etc.
Model AISC is specifically aimed at connection of an AIS receiver and other NMEA talkers to
Raymarine chart plotters, but there are many other uses as well. In this quick installation guide,
connection to a C- or E-series chart plotter is assumed. For use whith other than Raymarine C/E
series chart plotters, ignore the colour-coding on the front-label of the multiplexer and substitute
“chart plotter” for “C-series” or “C/E”.
For C-series AIS support a software upgrade is available from Raymarine. The baudrate of the
NMEA port of the chart plotter has to be set to 38400 (AIS).
For the connection of the C-series display to the Brookhouse multiplexer a cable with a special 5pin connector is required, Raymarine product code R08004.
Brookhouse NMEA multiplexer model AISC is supplied pre-configured, i.e. it is not necessary to
execute the setup procedure, unless one or more of the extra features are required, such as
filtering or conversion of NMEA sentences or a different baudrate conversion option is required.
We recommend to install the multiplexer first without setup to check if all functions are working.
The setup procedure is described elsewhere in this installation instruction.
Connections
Make sure that the wires are inserted in the correct screw terminals that correspond with the
descriptions on the front label of the multiplexer. A mistake can easily be made if looking at the
connector and label from an angle. Count the terminal screws and corresponding descriptions
from the end of the connector if in doubt.
Power supply: 9-35V. For practical reasons, power may be obtained from the Raymarine
Seatalk connector. If the Seatalk option has not been installed in the mux, do not connect the
Seatalk signal wire, just power (red +, black -). Also see Seatalk below.
AIS receiver or transponder:
NMEA OUT + (38400 baud) NMEA CH4 IN A
NMEA OUT - NMEA CH4 IN B
Brookhouse NMEA 0183 multiplexers can be used with a large range of AIS receivers and
transponders. Unfortunately the output signal characteristics of the various devices differ
significantly and some do not comply with NMEA (RS422) or RS232 standards.
The multiplexer’s NMEA input port for AIS is, like the other NMEA inputs, opto-isolated. The optoisolated port with the high baud rate 38400 requires signal characteristics, that fall in a narrower
acceptable range, than non-opto isolated ports. Therefore a given model AIS receiver or
transponder may work with a certain chart plotter or a computer port if directly connected, but
may not work if connected via the multiplexer. However, if the following simple instructions for
‘conditioning’ the output signal of certain receivers or transponders are followed, any compatibility
problems can be resolved.
Under the large green main multiplexer connector an insulated white wire (pig tail) can be found.
This wire is external, the mux enclosure does not need to be opened! The white pig tail can be
used to adapt the input impedance of the AIS input port for certain AIS receivers and
transponders. If this applies, remove the heatshrink insulation and combine the bare end with the
AIS output signal wire in NMEA ch4 IN A of the multiplexer.
Connect the following devices directly to the multiplexer’s AIS port (NMEA ch4 IN), without the
white adaptation wire:
Nauticast class A transponders.
Furuno class A transponders.
Standard Horizon GX2100 VHF with built-in AIS
Smart Radio AIS receivers.
Use the white adaptation wire as described above for the following:
All class B AIS transponders based on the SRT board (Comar CSB200, True Heading AIS-Ctrx,
Westmarine re-branded class B transponder, Simrad, etc.)
We also supply a separate 1K5 resistor, which should be used for some AIS
receivers/transponders in the following ways:
For the Nasa AIS engine.
Connect the 1k5 resistor as a “pull-up” resistor between NMEA ch4 IN A and the +12V
connection to the multiplexer. The receiver and the multiplexer should share the same 12V power
supply. Pin 2 of the AIS engine output port should also be connected to NMEA ch4 IN A, i.e. the
resistor and the signal wire are combined in this terminal.
Connect signal ground (pin 5 of the 9-pin connector) to NMEA ch4 IN B.
Do not use the white adaptation wire.
Other incompatible AIS output signals
Sometimes it is necessary to connect the 1K5 resistor in-line with the white adaptation wire, i.e.
do not combine the white adaptation wire with the AIS output signal wire directly, but connect the
resistor to the end of the white wire and combine the other side of the resistor with the AIS signal
wire in NMEA ch4 IN A. This is sometimes necessary for connecting an RS232 port, including a
PC port (for AIS emulation). There are also a few known cases where the resistor had to be used
in this way for connecting a SR161 AIS receiver.
We will also explain with photos how to make the AIS connections on our website under “tips and
suggestions”.
Other NMEA Talkers (4800 baud):
NMEA Output A + NMEA CH1 – CH3 IN A
NMEA Output B - NMEA CH1 – CH3 IN B
Note: If the Seatalk option has been installed and activated, CH1 is not available for NMEA input.
Leave open. (see Seatalk below).
Note 2: Standard NMEA talkers with baud rate 4800 can only be connected to NMEA IN 1, 2 and
3. NMEA IN 4 accepts baud rate 38400 for connection of an AIS receiver.
Seatalk
If the Seatalk option has been installed in mux model AIS-C, a direct connection to the Raymarine
Seatalk bus can be made. The multiplexer will translate Seatalk GPS and instrument data
received from the ST-bus to NMEA sentences independently and include this in the multiplexer
output data stream. This option is intended for installations including a computer. If the C-series
chartplotter is switched off, instrument and ST GPS data will still be available to the computer in
NMEA format via RS232 or USB.
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