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4-20mA Float Switch sensor


#1

Hi,
i am working on a project where i need to read a float sesnor and disply its value. In the real case the the float sensor is connected to a pump and it feeds the values directly to the pump. based on float sensor the pump turns on off. since last few months its showing some abnormal behavior ( random on off). i am things about readings the float sensor using arduino and chking whats going on… the float sensor is 4-20mA . whats the best way to connect this with an arduino.
Thanks


#2

@bucky56, Sorry but this is not an arduino forum. Now if you want to use a G80 then sure. Also, if you want to ask an generic electronics related question.

If the float sensor is in a wet environment it could be corrosion on the contacts.


#3

You need to grab the specs for the sensor - if it’s 4-20ma, it’s probably an ultrasonic sensor I.e. no contacts. That being the case you could stick any kind of data logger on it to read current/voltage. Are you reading a liquid or solid, is it water or something else? I have a couple of these, they usually come with a programming interface for setting min/max levels, etc… they typically run on 10-24 volts DC, make sure there’s no issues with supply voltage as well…


#4

Not the correct forum but if anyone else is playing around with 4-20mA and G30 etc etc, this will be useful.

If this is 4-20mA analog then you only need a sense resistor of either 100 or 250 ohms between your ADC input and ground. Use a 0.1% precision type.

Connect +24V to the + connection on the sensor and the - connection to your ADC and sense resistor. Now you get a current to voltage conversion. It won’t be from zero. For a 100 ohm resistor it will be 0.2 to 2.0 volts. Zero indicates the sensor is not connected so good for diagnostics.