by Santiago Salazar Chris Paulino 12/15/11 Florida Gulf Coast University Dr. Zalewski

Transcription

1 by Santiago Salazar Chris Paulino 12/15/11 Florida Gulf Coast University Dr. Zalewski

2 Previous project by Olexiy Kovtunenko and Robert Porter. They Created a LabView Program to communicate with 2 GPIB devices. The devices are a HP 34401A multimeter which gets voltage measurements, and a HP 53131A Universal Counter which counts the measurements per second. We planned to connect another GPIB device to the other two and have it communicate with the LabView program. The device is a HP 33120A Function / Arbitrary Waveform Generator. It generates waves with changeable settings HP 34401A multimeter HP 53131A Universal Counter HP 33120A Function / Arbitrary Waveform Generator

3 The waveform generator and the other GPIB devices are connected to the computer with GPIB cables. The GPIB cables are connected in serial fashion The cables on the multimeter and waveform generator are both connected to the cable on the counter. The cable on the counter is connected to the computer This allows them all to communicate with the computer

4 We used a BNC cable to connect the counter and the multimeter to the waveform generator. One BNC cable is connected from Channel 1 on the counter to Sync on the waveform generator. Instead of an ordinary BNC cable, the multimeter needed a BNC to Regular Battery cable. The BNC part is connected to Output on the waveform generator. The positive and negative battery connections are connected to the input on the multimeter.

5 The LabView program communicates with the GPIB devices by using string commands. An example of a command that can be sent to the waveform generator to control its settings: APPL:SIN 0.1 HZ, 1.0 VPP, 0 V Creates a sine wave at a frequency of 0.1 Hz, 1.00 VPP amplitude and a offset of 0 V. The wave, frequency, amplitude and offset can all be changed around. READ? is a command sent from the program to the counter and the multimeter to read the data each device is outputting.

6 The front panel of our LabView Program is shown below It displays a graph of the specified wave at the specified frequency which measures voltage against time. The Sample # text box reads from the counter and displays the number of measurements taken. Multimeter Data and Counter Data text boxes display the what is being outputted from each respective device. Only voltage can be used for the multimeter and we chose to use frequency for the counter. Either dc or ac voltage measuring can be selected from the radio buttons The address boxes are for the user to enter the address of each device so that the program can communicate with the devices. The program can be started and stopped on the front panel via buttons.

7 The block diagram of our LabView Program is shown below Mainly, it consists of a main while loop, which contains commands that ask the devices to send data measurements back to the PC Each iteration of the main while loop sends a single data measurement from both the multimeter and the counter back to the PC It also involves case structure used to select which type of voltage is to be read An event case structure sends commands to the waveform generator whenever the user click on the appropriate button Buttons are used to break the while loops When the main while loop is broken, the program stops running

8 We incorporated the ability to use generated waveforms. By using a BNC to regular battery cable to connect the multimeter with the waveform generator We added a Universal Counter to the other two GPIB devices and connected it to the waveform Generator with a regular BNC cable. However it only reads accurate data at frequencies of 10 Hz and above

9 We created a new LabView program that would work properly with the Universal Counter We added a textbox to display the output of the counter We added a textbox to display the number of measurements taken We added textboxes for the addressing of each GPIB device so that the user may change the address if necessary We added the ability to set the parameters of the waveform generator from the LabView program itself

10 We started the project not knowing how to interconnect the GPIB devices Another complication we encountered was how to send commands to the Waveform Generator The Universal Counter presented some technical problems as we found out it could only read 10 Hz and above when our project required much less than that We did research using the manuals of each device to figure out how to connect them and send commands to them Our project works almost exactly the way we want it to. The only problem is reading low frequencies from the counter as mentioned above