Seatalk to NMEA
All the NMEAXWiFi Multiplexers are able to convert SeaTalk1 datagrams to NMEA 0183 sentences.
This table shows which Seatalk Datagrams are converted to NMEA 0183 sentences:
Seatalk IN |
NMEA |
| 00 | $SDDBT |
| 10 | part of $WIMWV |
| 11 | $WIMWV |
| 20 | $VWVHW |
| 21 | $IIVLW |
| 22 | $IIVLW |
| 23 | $IIMTW |
| 25 | $IIVLW |
| 26 | $VWVHW |
| 27 | $IIMTW |
| 50 | part of $GPRMC |
| 51 | part of $GPRMC |
| 52 | part of $GPRMC |
| 53 | $GPRMC |
| 54 | part of $GPRMC |
| 56 | part of $GPRMC |
| 58 | part of $GPRMC |
| 99 | part of $GPRMC |
| 84 | $GPHDG or $GPHDM |
| 89 | $GPHDG or $GPHDM |
| 9C | $GPHDG or $GPHDM |
"$STALK"
In addition to the conversions shown above for "KNOWN" datagrams, the NMEA3WiFi multiplexer can convert Seatalk datagrams to the sentence "$STALK".
This message allows raw Seatalk data to be sent over NMEA without interpretation in the multiplexer. It allows for application developers to use Seatalk datagrams that are otherwise not translated to NMEA sentences. For example, the Autopilot datagram "84" will normally generate the NMEA \HDG/HDM sentence regarding heading data. But in addition, in Seatalk mode 1 it will also generate a raw $STALK sentence, allowing applications to determine what state the autopilot is in and other data.
The NMEA3WiFi multiplexer has four "levels" of $STALK capability.
- In the default mode, no $STALK messages will be sent in response to Seatalk Datagrams.
- In Mode 1, $STALK datagrams will be generated in response to
- datagrams 84 ,83, 87, 88,91,92,94 (autopilot information),
- 70,86 (keystrokes on remote)
- 01, A4 (equipment identification)
- In Mode 2, all datagrams will result in a $STALK message in addition to any of the conversions to standard NMEA messages as noted above.
- In Mode3 All conversions to standard NMEA sentences are turned off and ONLY $STALK sentences will be sent when Seatalk Mdatagrams are received.
TRANSMITTING $STALK
Because the NMEA3WiFI is completely bi-directional, it can accept NMEA $STALK sentences and send them out as Seatalk Datagrams. This allows application programs to -for example- simulate a Seatalk remote keypad.