MULTI-THERMOCOUPLE READER by fpf16947

VIEWS: 57 PAGES: 9

									 GRAND VALLEY STATE UNIVERSITY




MULTI-THERMOCOUPLE
       READER

         Version 1




       Brian Lillibridge
        August 2, 2002
                           TABLE of CONTENTS
Introduction                                   1

Setting up the apparatus                       2

Quick Start Guide (using Labview)              3

Specifications/Adjustments                     5

Wiring Diagrams                                8
                                  INTRODUCTION

        The purpose of this device was to have a dependable machine that would be easy
to use for teaching and student laboratory exercises. The device reads temperature versus
time and outputs the data into an Excel document. The data comes from 8 thermocouples
that are measured simultaneously with graphical and digital on-screen presentation. The
device plugs into the back of a computer (CPU) into the DAQ card via the ribbon cable
and type K thermocouples are attached to the device.




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                               SETTING UP THE APPARATUS

1.)   The Type ‘K’ thermocouple is attached to the FLUKE 80TK thermocouple
      module.

                    Negative         Positive




      Temperature
      Switch




2.)   The thermocouple module is connected to the device making sure that the
      positive and negative connections are hooked up respectively.

3.)   The ribbon cable (with the 50 pin adapter) is connected to the rear of the
      computer into the DAQ card.

4.)   The ends of each thermocouple should be placed into the positions desired to
      take the temperature measurements.

5.)   See the ‘Quick Start’ guide for using Labview to acquire the temperature data.




                                                                                     2
                           QUICK START GUIDE

1.)   Open Labview version 6i

2.)   Click ‘OK’ on the register screen and ‘OK’ the next screen

3.)   Click ‘Open VI’ and open the file ‘multi-thermo_reader.vi’ either from the
      CD given or from where it was downloaded.

4.)   The front panel is open showing 8 different graphs for each thermocouple.

5.)   Click on the ‘Operate value’ button in the tools palette (if the ‘Tools Palette’
      is not showing, go to ‘Window’  ‘Shows Tools Palette’).



                                  Operate
                                  Value




6.)   Make sure that the toggle switch is toggled up before running the software.



                Toggle
                Sw itch




                                                                                         3
   7.)    Click on the ‘Run’ arrow and the temperature will be displayed on their
          respective graph and digital display.


                            Run
                            Arrow




   8.)    When finished recording the temperatures, toggle the same switch back down
          and Labview will display a screen that asks where the file should be saved and
          what the filename is.

   9.)    Choose a location (ex – C:/temp/) and enter a filename (ex – filename.xls).

   NOTE: The ‘.XLS’ is crucial to have at the end of the filename for Excel to be able to
   open the data.

   10.)   Open Excel and open the file that was just recently saved.

   11.)   The temperature data is ordered in its respective position (Row 1 
          Thermocouple 1, Row 2  Thermocouple 2, etc.).



NOTE: This manual, the Labview file ‘multi-thermo_reader.vi’, and the AutoCAD
drawings can be downloaded at http://claymore.engineer.gvsu.edu. From here, go to
‘Undergrad student home pages’ and click on ‘B. Lillibridge.’




                                                                                        4
                  SPECIFICATIONS/ADJUSTMENTS

   I.      Specifications

The pin configuration for the DAQ card is shown in Figure 1 (below).

Figure 1 – The pin configuration for the DAQ card facing the back of the CPU
  pin 2




  pin 1




Table 1 – The legend for the pins used on the DAQ card for the device (pins not
mentioned are unused).
       Pin 1 – Analog input ACH0
       Pin 2 – Analog input ACH1
       Pin 3 – Analog input ACH2
       Pin 4 – Analog input ACH3
       Pin 5 – Analog input ACH4
       Pin 6 – Analog input ACH5
       Pin 7 – Analog input ACH6
       Pin 8 – Analog input ACH7
       Pin 9 – Analog input ground AISENSE/AIG

NOTE: Physical/Wiring diagrams are attached at the end of this manual


   II.     Adjustments

The timer is currently set to run 10 readings per second. In Labview, go to
‘Window’  ‘Show Diagram.’ This will show the details behind the graph.




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Each slot is represented by it’s own analog input cell. The I/O channel also corresponds
directly to the wiring diagram provided. The output is multiplied by 1000 to convert
from millivolts to volts. The voltage output is exactly the temperature in either degrees
Fahrenheit or Celsius.

Each output has its own graphical and digital representation and each slot is collected into
an array for the output into Excel.




                                                                                            6
The array is wired to the ‘2D data’ slot to get all 8 thermocouple measurements into the
same Excel spreadsheet.




To change the amount of readings per second, find the ‘Wait timer’ in the diagram at the
bottom.




It is currently set at 100ms. This means that the data points are taken once every 0.1
seconds or 10 readings a second. This can be adjusted to any desired rate.




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