Simrad NAC-3 Autopilot won't read Airmar WX220 Wind Data

[alloy]

On an offshore cruising sailboat we find it impossible to have a new Simrad NAC-3 autopilot computer read the wind information from a new Airmar WX220 weather station transducer. Both units are on the N2K backbone. The autopilot is controlled with a new Simrad AP-44 display. The AP-44 operating on the same N2K backbone properly displays the wind data and all of the other data output from the Airmar WX220. Putting the NAC-3 in "wind mode" gives an alarm "AP wind data missing".
Simrad technical support has over the last few months suggested numerous settings and items to check and confirm; none have solved the problem. Simrad is now stumped and states that it does not possess an Airmar WX220 and therefore is unable to investigate further. Airmar outputs wind data PNG 130306 and Simrad NAC-3 looks for wind data PNG 130306.
Anyone have a similar experience or suggestions to resolve the problem?

[Neptune's Gear]

Does the AP see the airmar as a valid source of data for wind? Look in network sources...

[alloy]

Matt, the AP-44 "sources" >"true wind">shows Airmar WX220 same for "apparent wind".

[KeelMe]

Is the 220WX on a backbone or a drop?

I see this fairly often on larger boats. The AP computer is usually the farthest device from the masthead sensor and can not see it.

The cause is typically the masthead sensor is on a drop not a backbone. But occasionally if micro cable is used throughout we have to split the system into two networks; Mast network and Boat Network.

An easy check is to plug something like your AP44 into the NMEA cable going to the AP computer. I use an Actisense NGT-1-USB for this.

[alloy]

Thanks Keelme. The WX220 is on an N2K drop (about 30 ft.) from the radar mast on the stern of a 43 foot sailboat. The drop connects to the backbone adjacent to the NAC-3 where, in a series of “T” connectors, the RF 25, AP44, 12vdc, NAC-3, OP-12 are also connected. Proper resistors are on the ends. The only NMEA 0183 input is a Furuno GP-32 GPS via the converter AT1. Precision 9 is also in the backbone.
I had ordered an NGT-1 (USB) and it should arrive today. I'll see what shows up there.
The AP44 input is N2K. Are you indicating there is a way to wire it to the NAC-3 nmea 0183 input?
Thanks

[KeelMe]

A drop should not be longer than 20 feet. Anything longer than 20 feet should be backbone.

The Airmar cables that are longer than 20' have a built in terminating resistor. If this is a drop that means you have three terminating resistors on the network. If you have three resistors than you are greatly degrading the network performance.

I was using the AP44 as an example of something that would be good to troubleshoot the network. What I meant was unplug the N2k cable going into the AP computer and plug that cable into the AP44 and see if you can see the 220WX from that point on the network.

When you get your NGT-1 get a gender changer for the N2k plug. You will use it a lot.

[alloy]

Thanks, Keelme. I have identified the Airmar WX220 drop cable as a WS2-C06 N2K cable that is 6 meters (20ft) long. Airmar specs indicate that only cables longer than this one have the built in resistor. Resistance measured at the NAC-3 is about 59.
The AP-44 is actually physically connected to the backbone further from the NAC-3 than the Airmar connection (if that is relevant?).
I'll find a gender changer.

[KeelMe]

Well, there goes that idea.

59 is great.

A few things I am thinking:
1. One of the offsets in the AP44 could be causing the problem.
2. Is there a plotter or other device that could be sending a different wind reference?
3. It's always a good idea to make the system as simple as possible when troubleshooting. I would disconnect the OP12 and GP32.
4. Calculate your voltage drop and make sure everything is in spec.
5. Make sure all of your grounds are good. Including N2k Power ground and NAC-3 Grounds.
6. Move the 220WX from drop to trunk with an inline terminator.

From my experience it is always something simple.

Good luck. Let me know if there is anything I can do to help.

[tanglewood]

My money is on a NAC-3 bug. There is probably something in the WX220 PGN that although acceptable to the AP44, is causing the NAC-3 to choke. It's too bad Simrad is too lazy to pursue this. Would it really be that hard to for them to go buy a WX220?

I think KeelMe's suggestion is good to strip the network down to something minimal just to test this particular thing. The WX, NAC, and AP44 would be ideal, and show that the AP44 can display the wind data, but the NAC doesn't accept it. Then you have two Simrad products, one of which can display the data and one that doesn't.

Your Actisense trace might give you a clue about what's "different" in the PGN that's causing the NAC to choke.

[alloy]

Thanks for the input and suggestions. Here is how I found and resolved the issue.
The Simrad NAC-3 failed to read and respond to the wind data from the Airmar 220WX weather station although the Simrad display, AP-44, displayed both true and apparent wind.
I resolved this by connecting an Actisense NGT-1 between the N2K backbone and a laptop with the the Airmar Weathercaster (WC) software loaded. WC displays the PGN outputs of the weather station. The wind data PGN is 130306. I assumed there is only one 130306 PGN, but WC showed 5 lines of data designated “wind data 130306”. Three were defaulted to “off” and not transmitting. The five are: 1. “wind speed and direction relative to true north”, 2. “wind speed and direction relative to magnetic north”, 3. “apparent wind speed and direction”, 4. “true wind speed and direction relative to ground referenced to bow of vessel”, and 5. “true wind speed and direction relative to the water referenced to bow of vessel”. The 220 WX was out of the box with #1 and #3 “transmitting”; #2, 4, and 5 were not transmitting. The NAC-3 began responding to wind data, both true and apparent, after enabling #4.
Note that Data #4 and #5 are referenced differently; our boat is not feeding “through the water speed” to the N2K so I assume #5 is irrelevant.
Airmar seemingly has no tech support and failed to respond to inquiries I sent. Simrad/Navico tech support was stumped and failed to suggest the above trouble shooting process over a 4 month inquiry period involving at 25 e-mail exchanges.

[KeelMe]

Congrats! Good to hear Alloy!

It's always something simple but finding that one simple thing can be tough.

I knew you would figure it out once you got your computer hooked up to the network.

Good job and thank you for keeping us updated. I will have to keep this in mind if I ever find myself troubleshooting a 220WX.

[Malcthom]

Hi Alloy.
I read with interest the resolution to your NAC 3 'wind data missing' issue.
I am having the same problem with a B&G WS320 coupled to a N2K network with NAC-3, Zeus 3 MFD, Triton 2 AP controller & keypad, bridged via a Yacht Devices YDNG-03 to a Nexus NX2 network for speed and depth inputs.

I can change the calculated wind output of the YDNG-03. At present it is set to any but I can select HDG_SOG which is field #4 on your system as far as I can tell.
Did you keep the other fields active #1 TWS, TWD relative to true north, #3 apparent wind?

Thanks

[alloy]

Sorry for the delay in responding. I can't recall (and can't check at the present time) which of the sentences are active. I assume you will try TWD and TWS alone to see what works. The Airmar has its own compass so the there could be a conflict if the computer is trying use two compasses to compute true wind functions.

[torrmundi]

I've replicated Alloy's results in my system (Navico NAC-3 autopilot computer, Airmar 220WX Weatherstation, Lowrance transom paddlewheel and Zeus 2 multifunction display).

I had three issues:
- NAC-3 would not allow me to use Wind mode of the autopilot (steering to maintain a constant apparent wind angle)
- Zeus 2 MFD would not allow me to switch the source for True Wind data between'This Display' (Zeus2) and 'WX Series WeatherStation Sensor'.
- null data report were generated by the Zeus 2 MFD for PGN 128259 (speed referenced to water, using the BSM-1 as a source. The BSM-1 (Broadband Sounder Module) on my boat uses an Airmar B164 sounder that does not have any speed function, only temperature and depth.

All issues are solved as follows:

Requirements:
- a speed over water sensor sending PGN 128259 Speed Water Reference on the N2K bus
- the Airmar 220WX must have three types of PGN 130306 Wind reports enabled:

• 0x00 “wind speed and direction relative to true north”,
• 0x02 “apparent wind speed and direction”,
• 0x03 “true wind speed and direction relative to ground referenced to bow of vessel”

The Airmar 220WX can be programmed with Airmar's Weathercaster app running on a Windows PC. However, this app is old and slow and cannot deal with much in the way of bus loads, not even 15-20%. So the solution is to setup a minimal bus with a single joiner, a single termination (the other is in the 220WX's cable), a USB Gateway e.g. Actisense NGT-1, a +12Vdc power plug and the 220WX.

• Start the app - it auto detects the COM port in use by the USB Gateway.
• Select Advanced Setup. Verify Source Sensor is "Weather".
• After the Weatherstation is identified by the app, Enable/Disable Functionality button will be enabled.
• Select Enable/Disable Functionality and scroll down to find PGN 130306. There are five rows for this PGN.
• Enable the first, third and fourth rows by setting the Interval to 0.5. Disable the second and fifth rows by setting the Interval to 0.0.
• Save, Close, and Exit the app.

An added benefit is that calculated current indications become available with the SOW sensor.

[alloy]

Further to Torrmundi's post on this matter, (sorry for the delay, we are now happily stranded in NZ because of Covid), our Airmar WX220 partially failed while still under warranty. Shipping and repair took about 6 months.



In the interim I bought and installed a LCJ Capteurs wind instrument that reads apparent and outputs nmea 0183 but adapts to N2k easily. My main use for the Airmar was not weather, but wind info input for the autopilot to helm the boat based on wind direction. I found the LCJ does that simply and excellently connected to the Simrad NAC-3 and simrad AP44 control head. FYI, we're a 43 foot monohull with traditional analog wind transducer at the masthead and analog displays. The LCJ is mounted on a stern radar mast 14 feet off the water. In addition to helming, the LCJ data via the AP44 and Furuno RD-33 displays true, apparent, "ground" wind.


The repaired Airmar has never been remounted and rides along in the bilge, and the useless "weathercaster" app is uninstalled.