How to install a LabJack (U3)?

A whole testing day, and here are my conclusions:

I have conditioned the signal my solar sensor gives, connecting a resistor across the solar cell terminals to drop voltage to a max 0.350 volts (350 mv), working this way in the constant comsumption zone, and making the voltage as a linear function of the solar radiation received. So my 100% solar is a 350 mv readout on the Labjack FIO2 terminal.

On WD Labjack sensors setup I


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Could my problem be 1-wire issue related?

just a recap
do you think one problem is that the U3 is reporting a mv reading when wd is expecting a v reading for the 1 solar
i.e if i *1000 the reading for the solar voltage from the U3 that would help
?

Maybe… We can test that way and see what happens.

Any sensor you could use with a U3 should give a maximum 3 volts signal. That is 3000 mv. So you can set it on the “A” selector (see below pic). “B” selector would then be usefulness. This way you can easily do the math: (current reading / “A” selector) * 100 = % solar.

Or you can put entire volts on “A” selector, and millivolts on “B” selector up to 3 decimal places. 0 “A” and 350 “B” should read as 0.350 volts, or 350 millivolts. I think this is where the mess is done.

First option is simple, clean and easy for the user to understand.


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what is the maximum voltage reading showing in the labjack setup in bright sunlight?

I can change it with an adjustable resistor, conditioning the signal in order to meet a linear proportional response. Right now it should be 0.350 v for my sensor.

ok, i think thats the problem
thats higher than what is expected (200mv)
i.e i need to change it so that you can set that 200 setting higher, i,e in your case, to 350
yes?

Yes, I think that should work.

But, why the 200 mv limit?

Hi
i missed this posting…

with the 1 wire solar via the 1 wire ADC, the reading did not get any higher than the 200

anyway, just checking the code, you can set it higher than 200 as it is now, yes?

also, for sawadee, i just need to add in the code to convert the voltage reading to temperature (*100 - 273.15) and it will work with the temperature sensor?

Yes, I can set it higher, there’s really no limit on the selector. But below 1.0 mv the solar oercentage becomes 0 all the time. And above 10.0 mv or so, it does the same. The setting I should need, 350.0 mv, always produces a 0% solar and 0 W/m2.

No way Brian, I ask you for a little more help on this please.

The facts:

  • All following referred to a WD 10.37c build 19 version.
  • WD-Labjack interface works fine. I can read the exact mv input at Labjack setup as compared to a digital multimeter readings connected directly to the U3 FIO2 terminals.
  • My solar sensor setup is correct, in the correct timezone, correct location, correct offsets, calculating the max possible w/m2 at the right time.

Well, if I’m not wrong, a current reading of 0.108 mv over a scale top set at 0.350 mv should give: (0.108 / 0.350) * 100 = 30.8% solar. WD gives me 0%. This is if I set 350.0 as max mv for Labjack solar sensor.

I tried with other significant max mv settings:

  • 175.0 mv (half scale, so double solar expected: 0% WD result).
  • 3.5 mv (100 times lower, just in case of a bug on units): (0.106 / 0.350) * 100 = 30.2% theorical. 3.0% WD result
  • 0.3 mv (aprox. 1000 times lower): 0% WD result.

Only the second setting seems to be doing something with a bit sense. I wait for a change in solar radiation to see if this is casualty or it follows a linear pattern… (time passes)…

Another readings over 3.5 max mv:

1.- (0.065 / 0.350) * 100 = 18.5% theorical. 1.9% WD result.
2.- (0.081 / 0.350) * 100 = 23.1% theorical. 2.3% WD result.
3.- (0.132 / 0.350) * 100 = 37.7% theorical. 3.8% WD result.
4.- (0.159 / 0.350) * 100 = 45.4% theorical. 4.5% WD result.

I think it is sufficient to see something clear: a 100 times lower max mv setting gives about 10 times lower solar reading. So I tried the obvious: set 10 times lower to see if I can get the correct reading: 35.0 mv as max in solar setup. Result is a 0% solar again.

Can you please take a look at this Brian? Whenever you want, I’m not in a hurry :slight_smile:

Thanks.

humm
try first build 20 (new .zip) as i found a conflict with 1 wire settings

and then next if still not working I will add in debug code to show at each step what is happening :wink:

Build 20 up and running. But it is nightime here now and there’s still some hours of darkness. I’ll tell you tomorrow (late today for you).

Good morning Brian…

We’ll have a bright sunny day today. Build 20 is still doing exactly the same. No changes.

ok, lets start looking at logging the data to see what is happening:
use this update:
http://www.weather-display.com/downloadfiles/WeatherD.zip
and then let me know what appears under view, ws2010/ws2500 data setup

Not sure if I have to change any data there…


Hi
no, do not click on any settings there

so, nothing is being logged about labjack solar?
thats is a clue then

do you have labjack solar ticked in the labjack setup and you have the switch on the solar setup?

Sorry Brian, maybe I did something wrong. I restarted and this is what I get. The volts reading is Ok.


next to try:
http://www.weather-display.com/downloadfiles/WeatherD.zip

Next for you…

Today there’s no log like yesterday, all I have is this you can see below. Anyway, there have been changes: values went higher at sometimes, but they are not still the desired ones:


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