By chineloso70
#33268
How to convert the analog reading of the Gravity Analog Dissolved Oxygen Sensor (SKU SEN0237) output to dissolved oxygen values?
I already read the both the product and wiki (https://wiki.dfrobot.com/Gravity__Analo ... 7#target_0) pages, but none of theese provide the actual formula which relates tension output and dissolve oxygen value. Although the wiki page gives a sample code to use the sample with an arduino, that's not what I am looking for. What I would like to know is the actual formula connecting voltage output and dissolved oxygen and also, if possible, how to insert temperature correction in this formula.

Thanks!
By chineloso70
#33291
Hello and thanks for the reply!
Unfortunately this datasheet says nothing about the DO value. Can you instruct me in how to use it to obtain the relation between DO value and output voltage of the sensor?
By yuyouliang2012
#33374
Hello, each probe is individually different, so there is no definitive formula. But you can get the special formula of your probe through the experiment. The steps are like follows:
1. Insert the probe into the water which has no oxygen. Then record the output voltage(V1) of the DO board.
2. Insert the probe into the water which has the saturation oxygen . Then record the output voltage(V2) of the DO board. Then find the saturated oxygen value(N2) corresponding to the water temperature on this link: https://lakestewardsofmaine.org/wp-cont ... -Table.pdf
For example, if the water temperature were 25℃,the saturated oxygen value is 8.3.
3. You will get two points: (V1,0), (V2,N2). So you could get the formula like: y = kx+b
k is the slope; b is the intercept
May this information could help you, thanks.
By chineloso70
#33376
Hello, yuyouliang2012
That was exactly the kind of information I wass looking for, so now I am almost able to build my own code.
However I have one more question: how to introduce temperature correction in this y=k*x+b formula?
Anyway, your tip was already really helpful, thanks