Question

Consider the circuit diagram below used to monitor the output of a pressure transducer using a data acquistion card. In this configuration a change in pressure applied ot the pressure transducer is converted into a change in voltage (vout) which is then measured by the DAQ. Pressure is converted to voltage in the transducer according to the following equation:

Vout = {sensitivity} * Pressure = {0.1 [V]/[psi]} * Pressure

Usisg the pressure/voltage relationship of the transducer and the DAQ information in the table below determine:

1) The smallest measurable pressure change using DAQ A and DAQ B

2) THe largest pressure that could be measured using DAQ A and DAQ B

Hint: THe DAQ will limit measurement based on the saturation volatge.

3) IF the pressure transducer is expected to see a sinusoidal varying pressure as shown below which DAQ should be used to best meeasure the pressure and Why?

DAQ A input +/- 10 V =20 Vfsr 12 bits Resolution 4.88E-3

DAQ B input +/- 2v = 4 Vfsr 8 bits Resolution 15.6 E-3

Problem 2 of 3: Digital Data Acquisition-Applying Voltage Resolution to Measuremen Consider the circuit diagram below used to monitor the output of a pressure transducer using a data acquisition card. In this configuration, a change in pressure applied to the pressure transducer is converted into a change in voltage (Vout) which is then measured by the DAQ Pressure is converted to voltage in the transducer according to the following equation: Vout - [sensitivity)- Pressure-0.1 *Pressure si Pressure Transducer DAQ Al1+ out Al1- Using the pressure/voltage relationship of the transducer and the DAQ information in table below, determine 1.) The smallest measurable pressure change using DAQ A and DAQ B 2.) The largest pressure that could be measured using DAQ A and DAQ HB Hint: The DAQ will limit mcasurement based on the saturation voltage DAQ input range [V DAQ Q DAQ Smallest measurable Maximum Pressure # of Resolution pressure (pressure Measurable Bits V resolution) [psi] psi] DAQA +/-10V-20 V 12 4.88E-3 15.6E-3 3.) If the pressure transducer is expected to see a sinusoidal varying pressure as shown below, which DAQ should be used to best measure the pressure and Why'? Answer Time s

Answer 1

1)

For DAQA

input +/- 10 V =20 V_fsr 12 bits Resolution 4.88E-3

Vout = {sensitivity} * Pressure = {0.1 [V]/[psi]} * Pressure

4.88 x 10^-3 = 0.1 x Pressure

Pressure = 0.0488 Psi

The smallest measurable pressure change using DAQ A is 0.0488 Psi

For DAQB

input +/- 2 V =4 V_fsr 8 bits Resolution 15.6E-3

Vout = {sensitivity} * Pressure = {0.1 [V]/[psi]} * Pressure

15.6 x 10^-3 = 0.1 x Pressure

Pressure = 0.156 Psi

The smallest measurable pressure change using DAQ A is 0.156 Psi

2)

Largest Measured Pressure Using DAQA

Vout = {sensitivity} * Pressure = {0.1 [V]/[psi]} * Pressure

20 = 0.1 x Pressure

Pressure = 200 Psi

The largest pressure that could be measured using DAQ A is 200 Psi

Largest Measured Pressure Using DAQB

Vout = {sensitivity} * Pressure = {0.1 [V]/[psi]} * Pressure

4 = 0.1 x Pressure

Pressure = 40 Psi

The largest pressure that could be measured using DAQ A is 40 Psi

c) DAQ 1 is presferred because it's 12 bit and can represent (2^12 = 4096 ) different discrete values helping to get a smooth sinusoidal voltage waveform(DAQ) to measure sinusoidal pressure waveform.

And it can also measure highest pressure. +-25 Psi x 0.1 = Vout

= +- 2.5 V

As it ranges from -10 to 10V.