[41south]

Hi all

I'm slowly progressing with building and testing. Today I hooked up my Davis anemometer (7911) which is from a Wizard III station. The wiring all checks out as per the usual diagrams, the direction pot is 20k and the reed switch is 1 pulse per rev. 

But .....

On the internal web server of the station I see direction changes, but no wind recorded at all.
On the TFT of the Rx unit there is nothing, no direction and no wind speed.

It's been running for a couple of hours with a slight breeze. I can see pulses on the black wire so wind should be recorded.

Am I right that JP2 and R6 are not required for my hardware?

I have windspeed_sensor set at type 30

What is the best way to debug this please?

[41south]

I just found this thread, assuming it is still correct then I think I need to remove the RJ11 connector and crimp on an RJ12 with the connections changed

https://meteocercal.info/forum/Thread-Fi...Duino-Pro2

[werk_ag]

Am I right that JP2 and R6 are not required for my hardware?

Yes, you are right.

I just found this thread, assuming it is still correct then I think I need to remove the RJ11 connector and crimp on an RJ12 with the connections changed

https://meteocercal.info/forum/Thread-Fi...Duino-Pro2

Yes, you will need to crimp a new RJ12 connector on the Davis cable to suite the required pinout on the TX RJ12 connector (which follows the Fine Offset pinout).

[41south]

Many thanks, perhaps a good one for the FAQ as that info was quite buried in forums

[AllyCat]

Many thanks, perhaps a good one for the FAQ   [or the Wiki]

Yes, +1.   I also had to "find out the hard way" that the Wind cable connections of the Davis need to be modified.

The problem is that Fine Offset and Davis have their Anemometer pulse (digital interrupt) and Direction Vane (Analogue) input connections swapped in the RJ11 plug.  With some microcontrollers this could be "fixed" purely within the software, but unfortunately the Arduino (Nano) appears to use separate dedicated pins for Analogue and Digital inputs.  It might be possible to "double up" (link) an analogue and digital pin (CMOS inputs have a very high input impedance) for each signal, but the Nano appears to have very limited interrupt capabilities (only two pins, one for the Anemometer the other for Rain?).  So it looks as if a (PCB) switch/link or plug rewiring may be the only solution.

Another difference is that Davis use a potentiometer (3-terminal voltage divider) whilst FO use a (2-terminal) variable resistance (which needs the addition of another resistor to make a voltage divider) for sensing the Wind Direction.  On the Weatherduino Transmitter PCB the variable resistance is connected to earth, with an additional resistance to the supply rail.  So there are two earth connections on the "RJ11" (4 contacts) part of the socket and the Davis plug must use another pin with an "RJ12" (6 contacts) connector for the supply voltage.  However, in the Fine Offset transmitters, the variable resistor is effectively connected to the supply rail, which could also be done with the Weatherduino transmitter (it's just necessary for the software to subtract the ADC value from 1023).

This could give several advantages; firstly the Davis and FO could use the same (4) pins with an RJ11 (4c) plug.  Also, there is an alternative version of the FO Wind Vane which appears to use Hall (semiconductor) switches instead of the 8 magnetic Reed switches.  I've never been able to test one, but it possibly NEEDS a positive voltage supply on the cable, in the same way that the Davis potentiometer needs both supply and ground connections (shared with the anemometer switch).  Similarly, the more recent Davis Anemometers now need both supply and ground rails to feed their Hall switch.

Cheers,  Alan.