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***Tom - Raymarine - Moderator***

Hello Bob,

Marine Traffic's a great tool but of limited use for diagnostics because the data is (largely) volunteer-gathered from receivers in peoples' homes and businesses and depends on your line-of-sight signal level to those locations, their internet connection, antenna quality etc.

Can you describe what you mean about the device jumping in and out of the network?
Every device should be listed every time you go into Select Device (as long as you're looking on the Master MFD, since only the Master talks on SeatalkNG); if everything else is listed every time but the AIS intermittently then you may have a problem with its connection into the network indeed. I wouldn't have thought that would be the backbone or termination because you'd likely see similar issues with other STNG devices if that were the case (especially the pilot, since each pilot module continually checks for connection with the other components); if it were an STNG problem then I'd look at the spur connecting the AIS to the rest of the network. The other feasible cause is restricted supply to the AIS, so perhaps it's browning out and rebooting when it tries to transmit.

The MFD won't show detailed STNG reliability information because most CANbus transceivers filter error frames at the hardware level and only pass good messages through to the CPU: the two tools to look at CANbus reliability at the signalling level are an oscilloscope and a dedicated CAN analyser. We strongly encourage our top-level technical service dealers to have both of these tools, which will clearly show an unhealthy network and report error frame counts.
If you'd like us to look and see whether the AIS is genuinely dissappearing from the network or whether it just appears to be in the diagnostic list, by all means log a period of STNG data in Diagnostics > Interfaces > STNG/N2K > Start Buffer / Record Buffer and post it back here. I'd be happy to have a look and see what devices are sending what traffic.

Regards,
Tom