ADS1115 SKU: PR33-10 data not linear

Hardware
1

I am testing a ADS1115 and I have an issue with the data. I am using a 4-20mA loop simulator to test the output. The board is set as follows;
Default address, Gain 2 (2.048v), mode continuous, rate_128
If I set the loop simulator to 4mA the device returns 6415 (expected), and setting the sim to 20mA the device returns 31930 (also expected) if I set the sim at 12mA I get 19,160 (not expected). I have tested with more that one loop simulator.

I expect I am missing something basic but why is the data output not linear?

2

This product is based on the INA196, which has a +/-3% error rate.

I would recommend doing a 3-point calibration. so take raw ADC values at 8,12,16mA and 16 mA, calculate the multiplication for each, and use that to convert future raw ADC values into mA

3

Will do and thank you for the prompt response.

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