Trouble with our ADS1115 Current Loop Receivers

Hello NCD,

I recently bought a few ADS1115s. They look perfectly suited for my application, but I’m having trouble getting them to work. The basic hardware setup is:

An NCD Single Channel ADS1115 connects to an NCD I2C Shield, which connects to a Raspberry Pi 3 Model B+. We intend to connect the current loop inputs to a HYDAC AS1008-C-000 Aqua Sensor. The aqua sensor’s model number is generalized as AS1000.

We’re getting whimsical, nearly random, readings from our setups. The problem must be in the current loop receiver or in the software because everything else is working properly. All our AS1000 Aqua Sensors, connecting cables, and wiring harnesses are known to work properly and have been tested with other equipment. The Raspberry Pi is also working properly. We even have an MCP4725 DAC connected to the I2C bus at a different address and it’s working properly, too. While diagnosing this problem we tried disconnecting the other device, of course, but the NCD receiver’s behavior did not change.

You included lengthy datasheets from Texas Instruments for their ADS1115 chip and INA196 current shunt monitor on the NCD receiver’s web page and we appreciate that. However, we could not find any documentation for the receiver board itself.

Could you please tell us which pins on our AS1000s connect to our NCD receiver’s terminals?
What are the correct jumper settings for our NCD receiver when connecting to our Raspberry Pi 3 B+?
What is the correct configuration for our setup (i.e. exactly what value should we send to the ADS1115’s configuration register prior to reading from its conversion register)?

Thank you very much.

John Lorenz

The wiring diagram can be found on product page under resources section.
I will recommend using this library

You will need to use the ADC as a single ended ADC.