NMEA 2000 bus crash

[george123]

Not sure if this belongs on the MFD or instrument forum.

Four years ago I installed a system that has the following; Furuno NavNet3D display, Simrad AC42/AP28 autopilot, WSO100 weather station, DST800 transducer, two NMEA2000 GPS antennas. The system worked great for 3 1/2 years. Six months ago I installed the a75 (software v16.47) display connected to the NMEA2000 backbone. The boat has not been used that much during the past six months. The a75 displayed all the NMEA2000 data that was on the buss. Four weeks ago something strange started to happen and that was randomly the NMEA buss would crash and all the data on the buss would be gone. The system crash would happen 20-40 minutes after the system was up a running. The DST800 would report correct information when everything was running. I started to trouble shoot the system and when I removed the DST800 from the buss the data for the other devices that were on the system would come back. So I concluded that I had a bad DST800. I have sent this back to airmar for evaluation and they have told me that the DST800 is fine. The only new device o the nmea2000 buss is the a75. Have you seen anything like this related to the a75

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum George,

We have not received any reports of a/c/e/eS/gS-Series MFDs crashing a SeaTalkng/NMEA 2000 bus. Should the problem be intermittent, then it may be challenging to identify the faulty component. The most common reasons for problems with a SeaTalkng/NMEA 2000 bus are:
- failure to properly terminate the SeaTalkng/NMEA 2000 backbone ... two terminators , one at each of the extreme ends of the backbone
-networking component failure ... inspect networking components for signs of corrosion or damage. Check components for pin/lead to pin/lead continuity and verify that no shorts are detected between pins/leads
- insufficient power ... verify that the power insertion point is located at the approximate mid-point of the backbone's LEN load. Verify that the batteries supplying the circuit are in good working order (load test) and have been fully charged. After fully charging the batteries, the system should be tested while the vessel is connected to shore power.
- ground loop ... resulting from improperly powering the SeaTalkng / NMEA 2000 backbone
- product failure ... Faulty products are most commonly be identified through fault isolation ... after verifying the above listed items, then the bus would be reduced to two components (recommend that you start with the devices at the extreme ends of the backbone). The system would then be exercised and when confident that these components are functioning, an additional component would be added (recommend adding components from the extreme ends of the backbone, working toward the middle of the backbone).

Should a faulty device or networking component identified, then it should either be replaced or serviced.

[george123]

Thanks when I get to the boat I will start troubleshooting. I plan to update the software in the a75 first next I will look at each device on the network.

[Chuck - Raymarine - Moderator]

You're welcome.

[george123]

I was thinking about this last night. The a75 has the ability to have a transducer connected to it so because of this it will be transmitting depth/speed/temp PGN's. Could this cause a conflict with the DST800 that is in the system? Should I be changing a device instance on one of the devices?

[george123]

How can I turn off a PGN on the a75? I can not find this feature in the manual. I am trying to trouble shoot a nmea2000 buss crashing.

[Chuck - Raymarine - Moderator]

George,

Unlike the a77 and a78 MFDs, the a75 MFD does not feature a transducer socket. Only when an a75 has been interfaced to one of the following will it transmit NMEA 2000 PGNs including depth, speed, and temperature data:
- CP100, CP370, CP470, CP570, DSM30, DSM30, CP300
- an ax7, ax8, cx7, e7D, ex7, eSx7, or eSx8 MFD
- a NMEA 0183 source of depth, speed, or temperature data.

[george123]

I looked at the nmea 2000 analizer data and the a75 is transmitting the depth pgn with no depth info. The Dst800 pgn is transmitting data and is being recited by the a75. So if I can turn off the pgn that is being tra smitten by the a75 I can troubleshoot the buss.I have no external box connected to the a75.

[Chuck - Raymarine - Moderator]

George,

Raymarine's MFDs do not have configuration settings to permit what is or is not transmitted to a NMEA 2000 backbone. Regarding use of a DST800 within a Raymarine system, an i70 MFID must be installed with these smart transducers to function as the Data Master for Speed, Temp, and Depth data from this transducer. Alarms, offsets, and calibration of the DST800 are all configured via the i70 MFID, not by the MFD.

[george123]

I understand the need to have the i70 if you have no other way to configure the dst800. I can configure the Dst800 from another device on the network. I have talked to Gemeco/Airmar and they believe this is the possible reason why I am getting the random buss crash.