Hi. I'm trying to interface a pH sensor which has a 0-5V output to arduino uno. However, the pH sensor has 2 voltage output, V positive and V negative. How do I connect this with Arduino to read the voltage output?
Hello momomola1
Read the data sheet of the sensor in use.
Have a nice day and enjoy coding in C++.
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A bare sensor can not be read by an Arduino board. You need a module for a PH sensor, such as this one: https://www.tindie.com/products/rezahussain/dormant-labs-ph-module-v2/
This is the one ? https://www.aliexpress.com/item/4000570786279.html
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So does a battery.... you can't have voltage with only one output, you always have two anyway, so that the voltage is measured at one point relative to the other.
Could Vout- not be Arduino ground and Vout+ would go to an analog input where an analogRead() would give 1023 for 5V or about 675 for 3.3V?
both output voltages are positive? if yes then you can use two pins directly and take the values of each pin.
if one of them is negative, make a inverting buffer having gain of -1 whil will make it positive (using opamp, you can search inverting configuration of opam for reference).
Does it make sense to talk about them being both positive or one being negative when there are only two connections? Both positive compared to what? If you stick the black probe of a meter on the so-called Vout- the meter will take that as "ground zero" so to speak, and the Vout+ will measure 5 or 3.3 on the red probe. The pic says the outputs are 0-5 or 0-3.3 (presumably you buy one or the other?) so the fact one side is called Vout- is no more a "real" negative than the flat side of a AAA battery is negative even though it's marked "-". Yes it's negative compared to the pip on the other end, but it's not negative in any global sense.
With three outputs it might be more tricky if the middle on was on the Arduino ground and the negative was actually negative wrt to that one.
that's why i told both cases, either way he can do 
Bit of a waste of time until we have confirmed the actual datasheet of the device which 6v6gt appears to have guessed. 
Hi. Thanks for the reply. Yes that's the sensor that I got. The sensor specifications are as followed:
I can't seem to find the datasheet anywhere but the link to the sensor is as followed:
That is also all the information that we can find.
Can you measure the voltages of Vout+ and Vout- with different Ph values (power the sensor with 5V), we probably can make a good guess.
Hmm. So which means to say, the pH Vout - connects to Arduino ground and the pH Vout + connects to analog input of the arduino? Do correct me if im wrong.
Even if the Vout- is internally connected to GND (Power negative), then I would connect it to a analog input to measure the voltage drop over the cable.
That's the way I see it.
But why don't you test it with power to the sensor and a volt meter or o'scope across the outputs. I would do that even if I was certain how it worked, just to double-check.
Sounds right
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