Weirdness (I think) with 4-20mA sensor and ADS1015

[stiebs]

I'm reading pressure from a SCUBA cylinder, which is gradually emptying as I change and discharge it .. so all my readings differ over time ..

But right now,
ADS is reading 2.594V
Voltage across the 200 ohm resistor is 2.51V
Voltage at the ADS input pin fluctuates while is connected, but if I disconnect just the ADS input, it also reads 2.51 (ie, across both the 200 ohm and 10k resistors)

The 10k is there from the suggestion in this post:

Reading 4 to 20ma pressure sensor using uno

The sensor is designed to drive 4 to 20 mA through the output circuit regardless of the sensor supply voltage (within the allowed limits). So, using a 250 Ohm resistor, Ohm's Law gives: 0.004A*250R = 1V 0.020A*250R = 5V A better circuit includes a 10K resistor for overvoltage protection at the input, and has the negative sensor power supply connected to Arduino ground, as follows: [sensor_conn.png]

Current as measured with multimeter is 12.53mA