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Seatalk Option (Seatalk bridge)

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The Seatalk Option for Brookhouse NMEA Multiplexers

Seatalk is the proprietry protocol used by RayMarine for communication between ST Marine Instruments. Brookhouse NMEA Multiplexers support this protocol, as a low-cost optional extra. If the Seatalk option is purchased when you order your Brookhouse Multiplexer, channel 1 can be configured (by the user) for connection of either an NMEA-talker or Raymarine Seatalk intruments. If set up for Seatalk, data is extracted from the Seatalk bus and converted to NMEA sentences before being output via the multiplexer's RS232 output-port. This function is often referred to as a "Seatalk-NMEA bridge". A single cable connects the NMEA Multiplexer with the Seatalk instruments. This single connection gives access to the data, produced by all Seatalk instruments on the Seatalk bus. On the remaining three Mux channels, other NMEA talkers can be connected.

The Brookhouse NMEA Multiplexer with Seatalk option provides 3 functions in one:

1. NMEA Multiplexer.

2. Seatalk-NMEA "bridge" (protocol converter). Seatalk-USB bridge if USB option is installed.

3. Seatalk & NMEA combiner.  

A typical situation is the following:

A yacht is equipped with Seatalk Wind Instruments, Depth Sounder and Log/Speed Instrument. The GPS is of a different make and provides NMEA output. Installation of an on-board laptop computer is planned and to make best use of all instrument and GPS data in the Laptop software (navigation s/w, optimum track calc, etc.), there is a requirement to combine and input instrument and GPS data in the computer in NMEA format. If a separate Seatalk-NMEA bridge would be used, an NMEA Multiplexer would still be required to combine the NMEA output of the bridge with NMEA data from the GPS. If the Brookhouse NMEA Multiplexer with Seatalk option is installed, no further electronics are necessary, which results in substantial cost savings.  

If the Seatalk option is purchased for the Brookhouse NMEA Multiplexer with compact user-programmable Repeater display, 5 functions become available:

1. NMEA Multiplexer.

2. NMEA Repeater Display  (Selected data)

3. Seatalk - NMEA "bridge" (Seatalk converter, selected data). Seatalk-USB bridge if USB option is installed.

4. Seatalk - NMEA combiner

5. Seatalk Repeater Display (selected data).

All data from result-sentences of the Seatalk-NMEA conversion can be displayed on the LCD. The user can select the display by pressing the selection pushbutton. Any of the displays can be set as the power-up default, simply by depressing and holding the selection-pushbutton until the word "Set" appears. For example, if a ST50 depth-sounder instrument has been installed and the navigator wants the "depth in feet" (or metres) displayed  at all times, this data can be selected as the power-up default.

Seatalk Connections

 There are several easy ways of connecting the Brookhouse Multiplexer to the Seatalk instruments. As all data is present on all Seatalk connectors on the instruments and on all interconnecting Seatalk cables, the signal can be picked up from any convenient point. Seatalk instruments always have two Seatalk connectors, to enable them to be "chained". The instruments at both ends of the Seatalk chain therefore have an unused connector. One of those connectors can be used to link the Seatalk bus to the NMEA Multiplexer (channel 1, Seatalk option enabled). A standard Seatalk cable with the required length can be purchased from the local RayMarine dealer for this purpose. These cables come with plugs at both ends. One plug has to be cut off so that the individual wires can be  inserted and fixed in the screw-terminals on the Brookhouse multiplexer.

The connection can also be made without the special cable, by cutting an existing Seatalk cable that connects 2 instruments and by making a simple splice. Click here to see how.

The following Seatalk data is extracted from the Seatalk bus and converted to NMEA by the Brookhouse Mux Seatalk option:

Seatalk-NMEA Bridge conversions

The range of Seatalk to NMEA conversions performed by the Brookhouse multiplexer includes all essential instrument data that can possibly be required by navigation software and has proved itself in practice on a variety of boats with different navigation software products.                                

In the mux setup menu, the user can select the NMEA ID for NMEA sentences that are the result of the Seatalk to NMEA conversion.

The filtering and editing feature, which is standard for all Brookhouse multiplexers, can also be applied to NMEA sentences that are the result of the Seatalk to NMEA conversion.  

Back to NMEA Multiplexers Product Overview 

Seatalk Technical Info, credits and disclaimer

There are no Seatalk technical specificatons available from the manufacturer. We have used the Technical Reference of the Seatalk protocol, compiled by Thomas Knauf Gmbh., thank you! All data in generated NMEA sentences has been checked against the data displayed by the Seatalk instruments, but we cannot accept liability for any personal injuiry or material damage due to malfunctioning.

  Note:  Seatalk is a trade-mark of RayMarine.