I have purchased 2 x DFR0972 I2C to 4-20mA output boards. I am unable to get any response from these boards at all. I have found a library for Micropython with example code at:

https://github.com/DFRobot/DFRobot_GP8302

But running this example on a Pi4 gives a error saying the device is not connected. When I run an I2Cdetect no I2C addresses are found. I have tried both DFR0972 boards, 2 different Pi4's and tried I2C connect from from 2 different Pi Pico's but I get no response on anything. I have also tried various different I2C pin connections on the Pi and Pi Pico without success.

Does the 24VDC supply need to be connected for board to respond on I2C? I assume it is using the 3.3 or 5VDC supply from the Pi for I2C comms.

Does the board have the required pull up resistors for the I2C network? I can find no mention of this in the documentation.

Any other suggestions before I toss these in the bin and go find something else?