This is getting more complicated than I thought it would be.
I'm almost tempted to get this:
Automation Direct FC-33 signal conditioner
page 2 has FC-33 tech specs
FC-33 Tech Specs, Page 2
Would I calibrate by smoothing the readings and mapping them?
That's what I've done with photoresistor readings via the ADC in the past (only used mapping).
My wire from the sensor is about 1.83 meters (6 ft long).
I found this article regarding the use of ADS1115 with Arduino
Arduino ADS1115 ADC Getting Started Tutorial
The PGA setting kind of gets confusing for me, I know it has to do with multiplying the voltages.
From the link above:
In the default mode, the setting is +/-6.144 volts.
Thus the value of 32767 would represent a value of 6.144 volts.
Dividing 6.144 volts by 32767 yields a scale factor of 0.1875 mV per bit. This is a significant improvement over the Arduino ADC which resolution of approximately 5 mV per bit. In fact, its about 26 times better!
The neat thing about this is that this is worst case. In another PGA setting, you can establish a full scale of +/- 2.048 volts. That provides us a resolution of 0.0635 mV.
ADS1115 Maximum Measurement Range
The PGA setting of +/- 6.144 range can be a little misleading as it seems to infer that you can measure voltages that high. You can’t.Instead, the maximum measurable voltage is established by the supply voltage to the chip. Specifically, the maximum measurable voltage is 0.3 volts more than the supply voltage. In fact, exceeding this voltage at your analog input may damage your chip.
Note the differentiation here between the PGA range and the maximum measurable voltage. The programmed range determines the value of a bit (or scale factor), while the maximum measurable range determines what your analog input can safely handle.
So i.e. if I were to use:
In another PGA setting, you can establish a full scale of +/- 2.048 volts. That provides us a resolution of 0.0635 mV.
Does that mean, for measuring I would use:
Full range is : 4.096 volts
Therefore:
.020 A * R = 4.096 V, R = 204.8 ohms
.004 A * 204.8 ohms = .8192 Volts