AIS 650 - STNG Output Not Working, NMEA Does.

[Chuck - Raymarine - Moderator]

Wimpress,

As the MFD is receiving GPS data via its SeaTalkng communications interface, you can indeed assume that the the MFD's SeaTalkng communications interface is operational and the SeaTalkng backbone is powered. However, it does not necessarily mean that the SeaTalkng backbone is properly terminated. A backbone which has not been properly terminated backbone may yield partial or intermittent communications. Accordingly, it is recommended that you verify that the SeaTalkng backbone has been properly terminated with a SeaTalkng Termination plug or SeaTalkng Inline Terminator at each of the backbone's two end nodes.

Q3) Assuming the STNG port on the AIS has indeed failed, why does its NMEA port also appear affected (limited to only NMEA 4800)? The AIS Installation Manual refers to "High Speed" and "Low Speed" ports, but does not identify them specifically as Port 1 or 2. I assumed the "High Speed" port is Port 1 on on the ProAIS configuration page, and set #1 at 38400 and #2 at 4800. Could this be a factor?
Q4) Will using 4800 baud transfer of AIS data really be noticed in the real world?

A3 / A4) You appear to have an incorrect understanding of the AIS650's NMEA 0183 ports. As configured at the factory, the AIS650's Port 1 is configured for 38400 BAUD NMEA 0183 communications and its Port 2 is configured for 4800 BAUD NMEA 0183 communications.
- The AIS650 is designed to multiplex data received via its 4800 BAUD NMEA 0183 input port - Port 2 (ex. 10Hz heading data, DSC VHF radio reports, multiplexed 4800 BAUD NMEA 0183 data, etc.) with NMEA 0183 AIS sentences and then transmit the combined data stream at 38400 BAUD via the AIS650's Port 1.
- Additionally, the AIS650 is designed to transmit data received via its 38400 BAUD NMEA 0183 input port - Port 1 (ex. GPS data, navigational data, instrument data, etc.) at 4800 BAUD via the AIS650's Port 2.

When interfaced in the manner specified above, this capability essentially provides the system with an additional bi-directional 4800 BAUD NMEA 0183 communications port. The AIS650/350/500/250's 4800 BAUD NMEA 0183 Port - Port 1 is most commonly used support bidirectional VHF radio communications within systems having a limited number of NMEA 0183 ports.

AIS receivers must communicate at the high data rates supported by 38400 BAUD NMEA 0183 or NMEA 2000 communications protocols to ensure sufficient data communications bandwidth to support the high bandwidth requirement of AIS data communications.

Q5) As before, the concern is whether or not the unit as a whole has been damaged or can be trusted as reliable.
A5) As indicated within the prior response, failure of the AIS650's SeaTalkng communications circuitry (assuming no other damage the AIS650) should have not effect upon its NMEA 0183 communications. Accordingly, should your AIS650 be interfaced to the MFD via NMEA 0183 communications as specified above and your MFD then be observed to be receiving AIS data, then can be assumed that the AIS650's NMEA 0183 Port 1 communications circuitry is operational. Similarly, should your AIS650 be interfaced to the MFD via NMEA 0183 communications as specified above and your MFD then be observed to be receiving data from a 4800 BAUD NMEA 0183 device or be observed to be providing data to 4800 BAUD NMEA 0183 listener, then can be assumed that the AIS650's NMEA 0183 Port 2 communications circuitry is operational.