Honeywell NBP series pressure sensor - How to get the pressure readings

Dear all,

I am trying to get pressure reading from the Honeywell NBPDLNN030PAUNV pressure sensor using a Arduino Mega board. This is an absolute pressure sensor measuring 0 to 30 PSI (Datasheet attached - Page 4, table 6, highlighted in yellow). I have used some analogue sensors (e.g. LM35) in past in with only 1 pin which gives the positive out voltage which we can use to get the temperature. This sensor has two voltage out pins one with Negative voltage (Vout-) and one with positive voltage (Vout+) (table 8 in the attached datasheet). Furthermore, the offset has a range of -7.0 mV to +7.0 mV and the sensitivity is also from 15.5 mV to 26.0 mv. I tried to take the pressure reading from both Vout- and Vout+ separately using the logic

  const float Null = 0.00; // Null VDC
  const float Sensitivity = 21.0;  // Sensitivity 
  pressure = analogRead(ADC_HONEYWELL);
  pressureVDC = (float)pressure * 0.0048828125; // (5/1024 = 0.0048828125)
  pressureVDC = pressureVDC - Null;
  pressurePSI = pressureVDC / Sensitivity * 1000;

None of the pin is giving me correct readings. Please let me know how should I write a code to obtain correct pressure readings. I have also searched on the internet but could not get any details about the code to get the pressure. Do I need to connect the Vout- and Vout+ pins some how and then take the pressure reading or do I need to include both Vout- and Vout+ in some logic to find the correct pressure readings.

I am novice to sensors/automation/electronics. Could someone please suggest me a good blog/tutorial/book which I can follow to get started in this field.

Waiting for your reply!!

Regards,
Himanshuws

NBPDLNN030PAUNV_PressureSensor.pdf (431 KB)

Looks like this sensor contains a Wheatstone bridge. U'll need an instrument amplifier (or two rail to rail OP.AMPs) to get good results. One example is the INA125 http://www.ti.com/lit/ds/symlink/ina125.pdf

The Honeywell NBP sensors are Wheatstone bridges without any amplification or signal conditioning of any kind. Therefore, you need to drive the bridge and amplify/condition the output yourself. A bridge output is the difference between two sides of the bridge, so you will need an instrumentation amplifier (in-amp) or discrete op-amps configured as an in-amp to do this. Simply measuring the output of one side of the bridge to ground will not give you the correct readings.

Look at this application node: http://sensing.honeywell.com/index.php?ci_id=143721