Gravity: Analog Electrical Conductivity Sensor PRO (K=1)

I am planning to use Gravity: Analog Electrical Conductivity Sensor PRO (K=1) for EC measurement with Mycodo set up. This probe is equipped with PT1000 temperature sensor. But the signal conversion board provided by default provides analog signal. So can be used only with ADS1115. But Mycodo input doesn’t have provision for PT1000 combined with ADS1115. So I am planning to use MAX31865 conversion board and use SPI interface for water temperature compensation.
Before I purchase I just want to confirm if my logic in doing so is correct or not? Or is there any other way to do it using the same sensor because after Atlas this is the only sensor that can work 24X7 when submerged in water. (Atleast the website says so.)

The output signals are 0 - 3 VDC, so you should be able to use it with any ADC that can measure in that range. There is not currently an Input module for this device, so you would have to develop a module with an ADC in order to acquire/store measurements.

What would be the problem if I use it under ADS1115:Generic analog pH/EC? Will there be an issue?

The problems will be the pH measurement will be erroneous because there is no pH probe/circuit and there is no code to measure temperature. The EC part of the module should work, but that’s speculative.

Sorry, I forgot to mention that I will be using Gravity: Analog pH Sensor / Meter Pro Kit V2 with ADS1115 along with this EC probe. The probe has PT1000 which is available in input section under MAX31865 on SPI interface. So is not it possible to use this method for temperature compensation?

The kit you mentioned in your original post already as hardware to convert the temperature to a voltage output. Why not just use that with the ADS1115 that you would already be using to measure voltage instead of buying another piece of hardware (MAX31865)?

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Oh… is it possible to use such a set up? I could not find an measurement with ADS1115 coupled with PT1000 (probe with Gravity EC sensor.). So I thought I must use an Input method that supports PT1000 and I found only on with MAX31865. Now what you suggest is to use any ADC channel and set Rescaled Measurment to Temperature? AM I right here?

An Input module that supports PT1000 temperature measurements using the ADS1115 doesn’t currently exist, but it looks like the kit comes with hardware to connect the temperature sensor that will output an analog voltage. You would have to add support for the temperature measurement, but that shouldn’t be too difficult. Simply copy the Input Module and make some modifications to start measuring temperature.

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Oh… I really would love to do that but I dont know how to do it. I think I will have to modify the ADS1115 input configuration? But still I dont know exactly what do I need to modify.

I managed to make a custom input with PT1000 and ADS1115. I just made some changes input_name_unique and input_name. Rest of the code I just copied as it is. It is imporetd into mycodo successfully. Is this enough or do I need to do more than this? Please let me know

Since the temperature probe is integrated with the EC probe, you should change the temperature compensation measurement to be acquired from the temperature probe rather than an Input selection. Temperature compensation should occur at every EC measurement.

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Yes… I got your point. If I set Period for Temp measurement equals to 5.0 seconds, Measurements to average to 3, and in EC /pH input I set Period to 15.0 seconds and temperature compensation max age to 15.0 seconds, will this work?

There isn’t a need for the Max Age option for temperature, since you should be acquiring the temperature measurement immediately before acquiring the EC/pH measurement, then using the temperature value to compensate. I’m not sure if what I’m saying is coming across, since I don’t know how familiar you are with how Mycodo Input modules are designed or your knowledge of Python. The module needs to be modified to remove the temperature options entirely (you are not acquiring temperature from an alternate Input), and use the temperature measurement from the probe for the EC and pH temperature compensation.

The probe has separate connections for EC output and temeprature output with two different measurement boards for EC and Temp. So I thought it can be considered as two different inputs coupled together. I thought they only have added an extra temperature probe with EC probe.

I hope my understanding is correct here.

The two EC wires connect to the EC board, which outputs 0 - 3 DC volts. The two Temperature wires connect to the temperature board, which outputs 0 - 3 DC volts. Both of these DC voltages are measured by the ADS1115. The ADS1115 can measure 4 analog voltages. So, the one input measures EC, pH, and Temperature (3 analog voltages of the 4 available). You connect your pH board, EC board, and Temperature board, which all output to the ADS1115.

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Yes. Thank you. That’s what I thought to do. I hope there wont be any compensation issue in this kind of set up.