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Pressure Monitoring System Issue
Reverse voltage Readings Issue of Sensors

Working with 4-20mA sensor www.omega.co.uk/pptst/PXM4200-I.html

with Transmitter https://store.ncd.io/product/1-channel-4-20ma-current-loop-transmitter-i2c-mini-module interface Raspberry Pi.

The major issue i have been facing that sensor is giving the reverse value. For example, at 4mA it is giving 5v (Max) and at 20mA it is giving 0v. i have check all my connections as well as code, but still not able to find out the cause.

Your Help will be much appreciated

By Curt Wuollet on 20 April, 2018 - 9:05 pm

Sounds just like a 4-20 ma. Current sink. Your load would go from the output to the positive supply terminal.

The absolute voltage across the load would then make sense.

Regards
cww

By Curt Wuollet on 20 April, 2018 - 9:09 pm

By the way, why do you have two transmitters?

Cww

You have choosen a 4-20mA transmitter that outputs 4-20mA over a range of DAC counts from 670 to 3460.

What you need is their 4-20mA receiver that will take a 4-20mA input and provide a DAC count.
https://store.ncd.io/product/1-channel-4-20-ma-current-loop-receiver-16-bit-ads1115-i2c-mini-module/

good luck