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Using the 4-20 Receiver

Newbie question:

Well, I got the 4-20 receiver for 3 sensors. I am using BeagBone and got also its I2C cape.  So BeagleBone is connected through the I2C to the 4-20 receiver, that is connected to 3 4-20 currnet look sensors.

How do I operate it? How do i get the current measurments from my 3 sensors?

Where can I find programming guide or user manuel?

B

Hi,

this board has an ADS1115 on the board. you can use this python lib to read the sensor values.

https://github.com/ControlEverythingCommunity/CE_PYTHON_LIB/tree/master/...

once you get the adc value you can check out this tutorial to convert these values into real world values.

http://old_learn.controleverything.com/industrial-4-20ma-current-loop-in...

Thanks

 

E

Thanks Bhaskar,

What i cann ot find is how to configure the ADC correctly for this board?  For example, the board has 3 4-20 inputs. How do i select which one to measure?  Missing all board-related configuration. Thanks

 

 

B

you will need to use the ADC as single ended. in the python code you can find all configurtion

https://github.com/ControlEverythingCommunity/CE_PYTHON_LIB/blob/master/...

To read 4-20mA you can use the ADS1115 in default mode. You can change the settings like bit resolution, sample rate based on your accuracy and speed requirement.

Thanks

 

E

Can I assume that for the first 4-20 input I need to cofigure 0x40 # Single-ended P = AIN0, N = GND,
for second input, 0x50 # Single-ended P = AIN1, N = GND

and for the third input 0x60 # Single-ended P = AIN2, N = GND

The phyton example just defines the command info but do not suggest what should be configured for this specifc board.

Thanks

 

Is that correct?

 

 

B

Yes, thats correct.

 

E

Any other configuration needed to the ADS1115 that are specific for this board?

J

For the life of me I cannot get this receiver to give me readings that make sense. If I just load the github code into my photon, and do not connect a transmitter, I get -4138 as a reading. If I connect a 4-20ma (0-100psi) pressure sensor to it, I get 26112. This really doesn't make sense because that means that every mA = 7562 bits, so there wouldn't be enough range to get us to 20mA?? Any help is appreciated.

B

HI,

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https://community.ncd.io/

Thanks