regarding 4-20mamp distance measuring sensor

i have a 4-20mamp water level sensor. it has 3 wire 1 is gnd other is vcc(24v) and 3rd is signal. and i want to interface it with arduino mega.
it has range of 0-15m
and accuracy is 2mm
so i want to help in connection and analog signal to distance conversion formula. actually help me in to display accurate distance on lcd

this is the sensor

38065-EN-VEGAPULS-WL61-Profibus-PA.pdf (345 KB)


A Mega has a 10-bit A/D, which means 2^10= 1024 steps.
15 meters in 2mm steps would need 7500 steps, or at least a 13-bit A/D.

To get that resolution, you must use an external A/D, like the 16-bit ADS1115 (15-bit single-ended).
Try Googling “Arduino 4-20mA ADS1115” for many options.
A Mega is overkill. An Uno or smaller form factor Arduino would be enough to read the sensor and drive the LCD.

It looks like a digirltal output is available.
If you have a profibus unit you need to get a profibus library to read the device output.

thanku so much.....
can i use a 250ohm resistor to convert 4-20mamp signal in 1-5v analog signal and after that ADS1115 16 bit analog to digital converter to convert that signal in digital form.

it will work????

how do i get stable digital ouput using ADS1115 16 bit ADC .

It seems you're cross-posting to get answers for this thread.
Cross-posting wastes out time, and is against forum rules.

An ADS1115 has several full scale ranges.
If you're using this board with a 5volt Arduino (Mega), then you can use the 4.096volt PGA 1 scale.
Max resolution of 4-20mA will be achieved with a 200 ohm sense resistor (4.096volt / 0.02A).
For a 3.3volt Arduino, a lower scale must be used, like the 2.048volt PGA2. That scale calculates to a 100 ohm sense resistor.
Post#10 here shows the diagram, with some protection.

how do i get stable digital ouput using ADS1115 16 bit ADC .

Give it a stable input and you will get a stable output.

Does indeed appear to be a cross post.

It is a sticky post at the top of every forum.
Read about subject lines

Threads merged.