B&G 508 Wind Sensor Intermittent (but VERY regular) Fault

[PeterBernard]

About 3 months ago, my B&G 508 Wind sensor started playing up, in a very specific way.

For so long as I leave it on, it remains stable.

If I switch it (well technically, my N2K network) off, and then back on again, every item on the N2K network comes back on faultlessly, but I have no wind data (speed or direction).

If I then switch it off and back on again, I get my wind data.

This happens every time - 100% reliably.

First time I switch on, nothing. Second time I switch on, wind data.

Until today, once it was switched on and working, it would remain on, faultlessly.

Today, while sailing, I lost wind data for the first time without having switched it off. It just dropped out.

I switched off the N2K network, and switched it back on again. No wind data, as usual. Off and back on again and got my data back . And it has remained stable ever since.

Any ideas what's going on or how to trouble shoot this?

I'm leaving on a 1,000 nm passage in just over a week, and would REALLY like to have some confidence in my wind data by then!!

Thanks in advance.

[Timfromli]

Did you ever resolve it? I am having similar issues. My B&G wind is working intermittently. I have not tried powering off the network though.

[PeterBernard]

No, never resolved it. Still a mystery.

[wingssail]

Just a hunch, this might be a software problem in the B&G system where the 508 does not exit the network cleanly on shut down. If that is the case it would likley be a B&G problem to fix.

[stevead]

this might be a software problem in the B&G system where the 508 does not exit the network cleanly on shut down

To the best of my knowledge there is no concept of a device "exiting" the network. Upon startup, devices claim an address and may/may not transmit a product information message however there is no such concept as "unclaiming or releasing" an address, nor of notifying other devices that it is "shutting down".

Double check/clean all of your NMEA 2000 connections/t-pieces, especially where the 508 joins the network. Remember that the 508 is inherently part of the backbone, so it includes the terminating resistor and connects to the backbone end of a T-piece rather than the drop-cable end of a T-piece. And you should only have one other terminating resistor located somewhere at the other end of your backbone.

If you want to get into the nitty gritty, here is a useful video describing how to electrically check your NMEA 2000 network.

https://www.youtube.com/watch?v=ulcKnrPmJqM

You could also try disconnecting other devices on the network and determine when they are reconnected if they are interfering with the 508.

Failing all of that if you have a B&G MFD (Zeus/Vulcan) on-board you may want to capture the data and open a support request with B&G. (The data capture is performed somewhere from the Settings->Network->NMEA 2000 menu item on the MFD).

The only way to really diagnose the problem is to log the actual NMEA 2000 messages being transmitted on the network.

Good luck.

[wingssail]

Originally Posted by stevead

To the best of my knowledge there is no concept of a device "exiting" the network. Upon startup, devices claim an address and may/may not transmit a product information message however there is no such concept as "unclaiming or releasing" an address, nor of notifying other devices that it is "shutting down"...

This is good information

[sailjumanji]

We had a problem with our NMEA network that showed up as intermittent fault with the B&G 608 wind instrument. I followed recommendation in this article for testing:

https://www.simrad-yachting.com/help...uideId=003-806

I built a test tool as specified in the Simrad article, and started doing termination tests to measure resistance. As specified in the troubleshooting article, the N2K network should have a resistance of 60 ohms. What I found is that our network was at 36-37 ohms, which suggests "too many terminators installed on the network." However what I found was a Noland canbus device that is used to get motor RPM's onto the network was failing. (It seemed to act like an additional terminator.) Once that was removed, everything on the network operated correctly.

I sent the canbus back to Noland, and they repaired it for free. Reinstalled and have not had any network problems since.

That all said, I do carry an extra wind sensor as these have a history of failing every 2-3 years. Similar experiences from other Seawind owners with B&G systems onboard.

[sjgharib]

bump.
Do you have a noise filter?
https://panbo.com/impedance-driven-n...-noise-filter/

[sjgharib]

So I have a similar issue with my 508 on a Hanse 415. I have something under my mast step that looks like a terminator, but according to Hanse it's supposed to be a noise filter...



Looking at the stock diagram, it calls out a SimRad noise filter. It adds another resistor to the network (bringing total resistance to 40 ohm) and adding a capacitor. The link i posted above talks to it specifically when they went to an N2k mast-top wind sensor that is the end of the network.



So I've ordered the filter to see if that is different.


Basically my 508 only comes to ilfe when you disconnect and reconnect after a power cycle on the N2k network. It's a brand new 508 (we replaced it at the end of last year), so I'm skeptical that it's the sensor. And it seems way too predictable to be the cable.