Grand Valley State University

Padnos School of Engineering

 

 

 

 

 

 

 

 

 

 

 

 

 

EGR 345 Lab 2

 

Introduction to LabVIEW and the DAQ cards

 

 

Josh Benson and Kristi Ghering

 

Sept. 12, 2000

 

 

 

1.         Introduction

 

The purpose of this lab exercise was to learn to use computers equipped with data acquisition cards and the LabVIEW programming language.

 

1.1       Equipment

 

The equipment used in this lab included:

 

Windows PC with LabVIEW software

National Instruments PCI-1200 data acquisition card and interface cable

Digital multi-meter

            Cadet circuit trainer breadboard and signal generator

            10KW and 2KW resistors

            One LED

 

 

2.         Procedure

 

2.1       Input Waveform

 

The signal generator on the circuit trainer was connected to an analog input on the DAQ board (ACH0) and the AIGND pin was connected to the ground of the circuit trainer.  A VI was created in LabVIEW to input the waveform and display it on a waveform chart.  This VI is shown in Fig. 1.  The filename is lab2_2.VI.

 

Figure 1: LabVIEW program to input and display a waveform

 

            Diagram:

 

                                                     

               

                Front Panel:

 

                               

 

 

The signal generator was set to output a low frequency sinusoidal waveform.  The program in Fig. 1 was run and observations were recorded.

 

2.1.1    Observations

 

Initially, the waveform chart showed a sinusoid wave with the peaks and valleys cut off.  The output level of the signal generator was reduced until the waveform appeared correctly with rounded peaks and valleys.

 

2.2       Voltage Control

 

The digital multi-meter’s positive lead was connected to the analog output pin DAC0OUT (pin 10) on the DAQ card.  The negative lead was connected to the AGND (pin 11) pin.  A LabVIEW program was created to control the voltage level of the analog output.  This program is shown in Fig. 2.  The filename is lab2_3.VI.

 

Figure 2: LabVIEW program to control voltage level

 

            Diagram:

 

                         

 

            Front Panel:

 

           

 

 

The program in Fig. 2 was run, and the knob on the front panel was manipulated. The observations recorded are described in the next section.

 

2.2.1        Observations

 

As the knob was manipulated, the front panel meter read the same value as the knob.  The digital multi-meter also read the same value as the knob, within .05 V.

 

2.3       Digital Input/Output

 

For this portion of the lab, the circuits shown in Fig. 3 were constructed on the circuit trainer board and connected to the indicated pins on the DAQ card. 

 

Figure 3: Digital Circuits.  DAQ card pin #’s in parenthesis

 

            Input:                                                    Output:

                                                                                    2K

                                                                                   

    +5V                                              PB0 (22)

 


PA0 (14)

                                                     DGND (13)

DGND(13)                 

    10K

 

 

The LabVIEW program shown in Fig. 4 was constructed and run.

 

Figure 4: LabVIEW Digital I/O program

 

Diagram:

 

 

Front Panel:

 

           

 

 

Observations were recorded as the program ran.

 

2.3.1        Observations

 

When this program was running, manipulating the toggle switch on the Front Panel to the “on” position caused the LED on the circuit board to light.  When the switch on the circuit board was placed in the “on” position the light on the Front Panel lit up.

 

 

 

 

 

3.         Conclusions

 

Through the completion of this lab exercise we have learned the basic tools necessary to perform data acquisition and control using a PC with LabVIEW software.  Specifically we have learned how to use the analog and digital inputs on a DAQ card.