4-20mA Pressure Transducer connection

I am attemting to connect my Industruino to a Pressure Transducer, SPT25-20-3000A, from  http://www.automationdirect.com/static/specs/prosensespt25transmitters.pdf

This is a 4-20mA device with a 9-36volt input range. The wire configuration on the transducer cable is Red, Black, White and Case Ground (bare wire). I am using the Red, Black and Case Ground.

My power source measures 12.2volts and is attached to the V+ and GND of the Industruino. The Industruino appears to be working well. So far I have tested Digital Inputs and Outputs without issue.

I have the Red wire of the transducer attached to V+ of the Industruino

I have the Black wire of the transducer attached to a 220ohm load resister.

The 220ohm load resister is attached to Analog Input-Ch1. (per the datasheet of the transducer)

I have the Case Ground attached to GND of the Industruino.

I cannot make the Analog CH1 Input work with the transducer with the following code:

#include <Indio.h>

#include <Class_define.h>

#include <Wire.h>

  float sensorVal1; //variables to hold your sensor data

void setup()

{  

  Serial.begin(9600); 

   while (!Serial)

   {

     // wait for serial port to connect. Needed for Leonardo only

   }

  Indio.setADCResolution(18); // Set the ADC resolution.

  Indio.analogReadMode(1, mA); // Set Analog-In CH1 to mA mode (0-20mA). 

}

void loop()

{

  sensorVal1=Indio.analogRead(1); //Read Analog-In CH1 

  Serial.print("CH1: "); //Print "CH" for human readability

  Serial.print(sensorVal1, 10); //Print data 

  Serial.print("\r\n"); // Print a new line to serial.

  delay(2000);

}

The output to the Serial Monitor is:

CH1: 0.0390000009

CH1: 0.0390000009

CH1: 0.0390000009

CH1: 0.0390000009

CH1: 0.0390000009

When I vary the pressure on the transducer, nothing changes.

Any ideas on what I am doing wrong?

Thanks ahead of time.

Steven

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Asked on 3/6/15, 11:25 PM

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