Easy IoT is a simplest IoT Solution presented by DFRobot
I have two Gravity DO sensors. My problem is ADC_V and DO value readouts are different among two. I bought 1st DO sensor from your agent in Japan, SWITCH SCIENCE. And I bought 2nd DO sensor directly from your online store.

I made saturated oxygen (SO) water by pumping air to the water for about 10 minutes. It's about 29 degree Celsius water. According to the table in your WIKI document, 29 degree Celsius water shall have the saturated DO value of 7.68 mg/L. I expected similar numbers from both sensors. 2nd sensor told similar number. But 1st one told totally different number.

I used the code in your WIKI document. I slightly made changes to the code, but basically the same as the original one.

My questions are :
(1)Which is the correct behavior?
(2)What causes the difference? Does the method of filling the solution cause such difference? The filling method are almost the same.
(3)How can I confirm if I make the correct sensor? I can prepare sensors following your WIKI document. But I'm not sure if those sensors are properly prepared.

Thank you,
Could you give me any possibilities which cause the difference of the behavior? Otherwise could you give me the method I can find the sensors with problems. If it's BAD, Japanese agent gives me another sensor. They said so. They also said they don't have any technical information about the sensor. So they need your decision. Please help me decide the sensor I bought from Japanese agent is BAD.