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Full Version: [CA11] AIS Lost Connection (C90W C12OW C140W)
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Hi All,
I have Raymarine C90W and C140W Chartplotters on my boat connected to a host of Maretron NMEA2000 devices via Seatalkng.

I recently added an ICOM M506 with AIS receiver on the N2K backbone.

With the radio / ais receiver connected I get "Connection Lost" messages on the chartplotters several times/minute.

This thread covers the problem well:


If the above thread is accurate then a proprietary heartbeat signal is expected from the ICOM radio and isn't being sent. I was hoping you folks could list what the heartbeat signals are supposed to be. I'll be adding a Raspberry PI to the N2K newtwork and If I knew what the packets are supposed to look like, I can fake the signal in Linux.
Welcome to the Raymarine Forum Brandon,

The reported symptom would not typically be caused by use of a third party AIS receiver/transceiver. C-Series Widescreen MFDs do not feature support for multiple sources of any one type of data within a system. This issue most commonly results from operating the MFDs with early software and/or having more than one source of GPS data within the system or a GPS data source which is intermittent. In this case both C-Series Widescreen MFDs feature internal GPS receivers. Should you desire to use the receiver within one of these MFDs as the system's source for GPS data, then it would be recommended that you ensure that its installation location has afforded the MFD an unobstructed view of the skies overhead. The internal GPS sensor of the other MFD should be configured OFF. If the system has been interfaced to an external GPS sensor, then the internal GPS receivers of both MFDs should be configured OFF.

The reported issue may also occur if the only AIS target within range is on the edge of reception range, causing reports to be intermittent. In the case of the latter, it would be recommended that the AIS dangerous targets alarm be configured OFF until the situation abates.
Thanks Chuck,
Sorry for not including a full list of electronics...I didn't want to bore anyone.
My system is currently configured with a C140W at the helm acting as master, connected to a C90W inside at the nav station. The two MFDs are connected to Raymarine Digital Radar and each other via SeaTalk HS (ethernet switch). The C140W is connected to the N2K backbone via SeaTalk NG --> N2k adapter. The Only source of GPS data is the C140W's internal gps. The C90W has internal GPS disabled and is usually powered off. The symptoms I'm describing occur both with the C90W on and off.

I recently completed a passage from Boston to Bermuda and back. The "AIS Lost connection" alarm does not seem to occur in Boston Harbor (Where there are plethura of targets...so I think your explanation here fits my situation:

If this problem could be mitigated by sending the MFD "heartbeat communications (proprietary)" referenced by the Raymarine Moderator in this thread: http://raymarine.ning.com/forum/topics/c...onnection, I would like information on what that signal is to see if I can duplicate it.


Unfortunately, being proprietary, this PGN is owned by Raymarine and may not be shared with any third party.
I've reconnected the Icom M506 to the N2k backbone and done a bit more testing.

Even in Boston Harbor where there are always at least 9 AIS contacts, I still get the "AIS Lost connection" Error message.

I only have one source of GPS data and that is the internal GPS on the C140W.

I don't believe either of the two explanations is accurate.

here is an exhaustive list of my electronics:

Raymarine C140W MFD (Connected to N2K backbone via SeaTalkNG adapter)
Raymarine Digital Radar (connected via SeaTalk HS (Ethernet switch))
Raymarine C90W MFD (usually off. When on: slave mode with internal GPS disabled)
Icom M506 VHF with AIS receiver and N2k output.
Maretrom DSM-150 (x2)
Maretron WSO100 (Wind direction/speed/etc..)
Maretron DST110 (Depth/Speed/Temp Triducer)

Short of configuring the MFD's AIS Dangerous Targets Alarm to OFF, no configuration settings of the MFD can address the reported issue. The feature which you are describing may indeed be resulting from insufficient GPS signal. While not weak enough to trigger a GPS alarm, it may trigger the alarm reported. Additionally, the long retired C-Series Widescreen MFDs were one of the early Raymarine MFD designs supporting limited NMEA 2000 communications. It is possible that the feature reported may simply feature of the design when interfaced via NMEA 2000 communications. As a course of action, it would be recommended that:
- the software level within each of the C-Series Widescreen MFDs be examined to ensure that the software within each MFD has been updated with the latest available Raymarine product software update.
- inspect the installation location be to ensure that the MFD has been afforded an unobstructed view of the skies overhead. It is not uncommon for a bimini top to reduce the strength of the received GPS signal to a level which is lower than that that which the MFD's internal GPS receiver can maintain a quality GPS signal. Under normal conditions, it would be expected that the HDOP for GPS position FIX produced by the MFD's the internal GPS receiver will be 1.0 or less. If higher, then it may be advisable to consider installation of an external GPS receiver.
- given the information provided within the opening paragraph, consider interfacing the third party VHF radio / AIS receiver via NMEA 0183 rather than NMEA 2000 communications. The system should not be simultaneously interfaced to the VHF radio / AIS receiver via both NMEA 0183 and NMEA 2000 communications protocols.
Should you you elect to test the performance of the system when interfaced via NMEA 0183 communications, then the VHF radio / AIS receiver should be disconnected from the NMEA 2000 backbone.
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