Posted: Wed Apr 22, 2015 11:11 am Post subject: How is Seatalk data multiplexed?
I've been looking at this multiplexer and it seems great that it can both read _and_ write Seatalk data (allowing me to replace my existing Raymarine Seatalk - NMEA bridge). What is not entirely clear to me, is how the seatalk data is actually routed?
For NMEA data, you can extensively filter data, specifying each NMEA port and the USB port as sources or targets. I would expect that Seatalk port to also show up in both input and output port lists, but the documentation suggests it doesn't.
So is data coming in from all NMEA ports translated to Seatalk, and Seatalk data translated to NMEA and sent out on all output ports? I understand that the Seatalk port itself can be filtered, but I'm wondering if there is any way to do routing as well?
Joined: Mar 26, 2006 Posts: 419 Location: Mannheim / Germany
Posted: Wed Apr 22, 2015 8:50 pm Post subject:
Well - i just have not made a filter for different seatalk sentences.
Sure - could be done. I just didn't have the time and - up to now - nobody asked for it.
What we have it a few diffentent configuration options.
So you can switch on/off things like
Seatalk -> NMEA
- create and send a HDM sentence, when appropriate data is received from SeaTalk
- create and send a RMC sentence, when appropriate data is received from SeaTalk
- create and send a VLW sentence, when appropriate data is received from SeaTalk
NMEA -> Seatalk
- create a SOG SeaTalk datagram, when appropriate data is available from NMEA.
Since SeaTalk and NMEA data not allways come in the same structure, it would be a bit more difficult. We would have to think about how to set up a filter for this.
Example : NMEA RMC sentence contains speed, position, heading, time, date - all in one sentence.
In SeaTalk this information will be in different datagrams.
You see. You can, to some degree, switch on/off creation of NMEA or SeaTalk sentences, but you can not filter to which port this newly created NMEA sentence should be sent to. It will be sent to all.
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