Wind sensor wiring

[Black Sheep]

I have a wind direction/speed sensor. I believe it's the NASA unit, and I believe it's supposed to spit out NMEA. I would like to wire it up, and squirt the NMEA at an Arduino board for a project.

My problem is that I don't know what each wire does. I could just experiment, but I don't want to blow anything up by pushing 12v the wrong way up a delicate signal wire!

The sensor has a 5 terminal DIN socket on its lead. The extension wire has a 5 terminal DIN plug at one end. The other end has five wires:
- thin red
- thin black
- thin blue
- thin white
- thick black

It looks as though the thick black is connected to the braid of the cable.

My first thought was that thin red & thin black were power; thick black signal ground? And white & blue NMEA out. But a multimeter between thin red & thin black shows no circuit. Between thin red and thick black, I'm getting about 400 ohms. So it looks as though that's the power supply?

Which two wires (black/blue/white) do I use for NMEA?

I've looked online but haven't found anything useful, so hoping someone on here can tell me for sure!

 

[earlybird]

Don't know the NASA particulars, but does the sensor generate NMEA sentences, but rather speed pulses and direction voltages? That's what the Raymarine sensor does. The display handles these signals, producing Seatalk and NMEA output.

 

[pvb]

That's the early, Mk 1 version. It doesn't output NMEA.

 

[Black Sheep]

Ah bu99er. Just responding to earlybird's post, I noticed that although the newer NASA unit sends NMEA, they did refer to an older 5 wire unit which doesn't. Don't know why I didn't see that earlier!

Thanks very much both - though it wasn't the answer I wanted!

Now to work out whether I'll be able to take the analogue inputs and do something with them!

Edit: I've just found a thread from 2007:
Which was updated in 2011 with the following information:

Screen is negative - use for neg probe
Red is power supply and should show 5v
Black varies between 1v and 4v
Blue varies between 1v and 4v
White pulses, but you won't be able to read anything on a meter.

That should get me going - and I'm very grateful to Ru88ell for telling me to use 5v not 12v!

 

[sgr143]

If you can find an electronically-minded friend with an oscilloscope (or one of those "picoscope" gizmos that interfaces to a laptop), it helps a lot.
The blue and black line are sine and cosine of the wind direction - so they should show sinusoidal curves 90 degree out of phase with each other as you rotate the vane through 360 degrees.
On the Raymarine head on my boat, the windspeed line (white on yours) show spike pulses downwards from 5V, with the pulse frequency increasing with wind speed. Yours may be similar.
I tested it powered up at 0 and 5V on the bench, by using a fan heater (on cold) to spin the anemometer cups and twiddling the wind vane by hand, while using a borrowed picoscope to see what was going on on the various lines.

 

[Black Sheep]

Thank you - that's incredibly helpful. I'd naively assumed the black & red gave a steady voltage 0-5v for 0-180 degrees one side or other. Maybe wishful thinking as that would be easy to read! It's about time I sourced a laptop scope - I've always wanted an oscilloscope since O level electronics! Now's my excuse. That would help me to understand what's going on, an how to get it into an Arduino. Worth the effort, as I have two of these, though one is only good for wind direction, having lost its cups.

 

[pvb]

I have two of these, though one is only good for wind direction, having lost its cups.

That's a standard Nasa feature!

 

[sgr143]

It's about time I sourced a laptop scope - I've always wanted an oscilloscope since O level electronics! Now's my excuse.

USB oscilloscopes & mixed signal oscilloscopes
is what my friend lent me. He knows what he's about - he designs real-time diagnostic electronics for fusion reactors... also he fixed my "unrepairable" (Thanks a bunch, Raymarine) wind instrument display unit for me; diagnosing which chip had failed, carefully unsoldering it from the PCB (14 legs, I think) and putting a new one in.

 

[cpedw]

USB oscilloscopes & mixed signal oscilloscopes
is what my friend lent me. He knows what he's about - he designs real-time diagnostic electronics for fusion reactors... also he fixed my "unrepairable" (Thanks a bunch, Raymarine) wind instrument display unit for me; diagnosing which chip had failed, carefully unsoldering it from the PCB (14 legs, I think) and putting a new one in.

For an entry level PC scope, consider PCB Scope for £16. It's amazing for the price, though obviously a bit limited in frequency range.

 

[MikeCC]

Although the older wind sensors did not output NMEA, the display does, via the repeater socket. Just make sure it's intended for the 5 wire sensor.