Figure 10: Data acquisition loops of Combined Control.vi



Figure 10: Data acquisition loops of “Combined control.vi”

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Figure 11: Setting magnet control voltage and measuring field

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Figure 12: Temperature measurement screen

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Appendix: The “Devchar” directory

The directory “Devchar” is located within the LabView directory on the C drive. “Devchar” contains the program “Combined control.vi” as well as the auxilliary programs “KE213 Voltage Controller.vi”, “one smu operation.vi”, “set Contrl Voltge Read back Field.vi”, “Temperature controller.vi”, and “Two smus operation.vi”.

Also, within directory Devchar is the subdirectory “System vi’s”. This directory contains all the subroutines utilized by “Combined control.vi”, “KE213 Voltage Controller.vi”, “one smu operation.vi”, “set Contrl Voltge Read back Field.vi”, “Temperature controller.vi”, and “Two smus operation.vi”. The files within subdirectory “System vi’s” are absolutetly essential for operation of “Combined control.vi” and the other programs.

The sub-directory “Data” under directory Devchar was used during program development to save SMU configuration files and the comma delimited spreadsheet files created during data acquisition. It is strongly recommended that all data files be saved in user created project directories located outside of the Devchar directory. By adopting this practice the accidental overwrite of critical program files can be avoided.

Location of directory Devchar and a list of the directory/files it contains:

C:

Labview --------------------------------------------------------------directory

Devchar ---------------------------------------------------directory

Data ---------------------------------------------------directory

System vi’s ----------------------------------------directory

diode curve.llb -----------------------------file

Ke213.llb -----------------------------file

Ke236.llb -----------------------------file

Magnet&Temp control.llb -------file

transistor_curves.llb ------------------file

Combined control.vi -----------------------------file

KE213 Voltage Controller.vi ------------------file

one smu operation.vi -----------------------------file

set Contrl Voltge Read back Field.vi -------file

Temperature controller.vi ------------------file

Two smus operation.vi -----------------------------file

Appendix: The files of sub-directory “System vi’s”

The five files within sub-directory “System vi’s” are type .llb files (LabView, vi library files). A .llb file is a collection of .vi files which have been appended together. The file types .llb and .vi are constructs of LabView. They are compiled files of LabView G code written to perform specific data acquisition and/or data manipulation tasks. They are created by a user within the LabView “environment”, and they can only be run within the LabView “environment”. What this means is that a LabView created program will not work on a computer system unless the LabView system files are present and running in the background. LabView is thus a sub-operating system within Windows which only reads, creates, and executes files of the type types .llb and .vi .

The file type .llb is a collection of LabView executable files of the type .vi which have been appended together. Within LabView you are allowed to list the .vi files contained within a .llb file. LabView will also allow you to open a specific .vi contained within a .llb file. The Windows program “Windows Explorer” will not allow you to see the contents, let alone open, a vi contained within a LabView .llb file. When first learning how to use LabView (writing LabView G code programs, saving LabView programs, and executing LabView programs) it’s easy to confuse a LabView .llb file with a Windows directory.

Listed below are the vi’s contained within each of the five .llb files of subdirectory “System vi’s” . These lists should prove convenient should it become necessary to re-load the “Combined control” files from the back up disks. When running “Combined control” or any of the auxiliary programs immediately following their transfer from the back up disks, LabView will ask the user to specify the location of all relevant .vi type programs. LabView will present the user with a browser to locate the vi’s.

Contents of “diode curve.llb”

Global - 1 SMU, results of sweep.vi

one smu 1st screen.vi

one smu 2nd screen.vi

one smu 3rd screen.vi

one SMU edit Screen (ver 4/9/97).vi

one smu error loop.vi

one smu Run sweep configuration.vi

one smu.vi

Contents of “Ke213.llb”

KEI213 Buffer Mode Setup.vi

KEI213 Calibration.vi

KEI213 Data to Buffer.vi

KEI213 Digital I/O Control.vi

KEI213 Direct Mode.vi

KEI213 Indirect Mode.vi

KEI213 SRQ Control.vi

KEI213 Status.vi

KEI213 System Parameters.vi

KEI213 Trigger Mask Control.vi

Contents of “Ke236.llb”

Keith 236 Set SRQ Conditions.vi

Keith 236 Basic Config.vi

Keith 236 Device Errors.vi

Keith 236 Display Message.vi

Keith 236 Fixed Level Pulse.vi

Keith 236 Fixed Level.vi

Keith 236 Lin’r Stair Pulsed.vi

Keith 236 Linear Stair.vi

Keith 236 Log Stair Pulsed.vi

Keith 236 Log Stair.vi

Keith 236 Modify Sweep.vi

Keith 236 Operate/Standby.vi

Keith 236 Read Measurement (modified 12/18/96).vi

Keith 236 Read Measurement.vi

Keith 236 Read Measurements (version 021097).vi

Keith 236 Read pulse diode Measurement.vi

Keith 236 Read pulse Measurements (rev020797).vi

Keith 236 Receive Message.vi

Keith 236 Reset.vi

Keith 236 Send Message.vi

Keith 236 Send Trigger.vi

Keith 236 Trigger Setup.vi

Contents of “Magnet&Temp control.llb”

setup magnet sweep (rev 4/15/97).vi

choose smu operation.vi

control temp has been set.vi

Display graph option screen.vi

Global - master cluster (ver 4/11/97).vi

Global - program flow controls.vi

options menu.vi

Second menu in Main.vi

Serial Communication.vi

setup temperature sweep.vi

Sweep temp & field, measure parametrics (041697).vi

Temperature control.vi

Teslameter Field Reading.vi

Total output vectors.vi

two D array in----one D array out.vi

Unified Control.vi

Wait for field to settle down then measure.vi

Contents of “transistor_curves.llb”

2 smu separate unsign integer string and convert.vi

Global - 1 SMU, results of sweep.vi

Global - 2SMU Instr1 fixed configuration data.vi

Global - 2SMU Instr1 X Array.vi

Global - 2SMU Instr1 Y Array.vi

Global - 2SMU Instr2 X-Array.vi

Global - 2SMU Instr2 fixed configuration data.vi

Global - 2SMU Instr2 Y-Array.vi

Global - 2SMU config string.vi

Global - 2SMU Instr1 Config cluster.vi

Global - 2SMU Instr2 Config cluster.vi

Global - 2SMU QUIT.vi

Global - 2SMU What next?.vi

Two smus Run sweep configuration.vi

Two smus.vi

two D array in....one D array out.vi

two smu wait message.vi

Two smus 1st screen.vi

Two smus 2nd screen.vi

Two smus 3rd screen.vi

Two smus construct data array.vi

Two smus create new sweep file.vi

Two smus edit Screen (ver 4/8/97).vi

Two smus edit Screen.vi

two smus error loop.vi

two smus error msg 01.vi

two smus error msg 02.vi

Two smus Examine sweep results .vi

Two smus expand 1D array into larger 1D array.vi

Two smus load setup (ver 4/8/97).vi

Two smus load setup.vi

two smus Round down to 4 digits.vi

two smus separate string.vi

two smus calculate source range from range inputs.vi

two smus separate floating point string and convert.vi

Appendix: The Auxillary programs

In addition to the program “Combined control.vi”, directory “Devchar” contains the auxilliary programs “KE213 Voltage Controller.vi”, “one smu operation.vi”, “set Contrl Voltge Read back Field.vi”, “Temperature controller.vi”, and “Two smus operation.vi”. To open any one of these programs first click on “File” within the menu bar of a LabView window. A menu will then open up. Click on “Open” within the “File” menu. A browser screen will then appear allowing you to locate the file.

A description of each of the auxiliary programs follows.

“KE213 Voltage Controller.vi”

Controls the Keithley 213 Quad Voltage Source and no other instrument. Use with a multimeter connected to selected port of Quad Voltage Source in order to verify GPIB operation.

“one smu operation.vi”

Controls a single Keithley 236 Source Measure Unit (SMU). Program allows user to select address of instrument he/she wishes to communicate with.

Program allows user to create an SMU configuration file which can be saved and recalled for use by “Combined Control.vi” as well as by “one smu operation.vi”. User is prompted to give configuration file a name when saving.

Program runs the sweep type specified by user and graphically displays results on monitor.

Program allows user to save sweep run data to a comma delimited spreadsheet file. User is prompted by program to give the spread sheet file a name.

“Set Contrl Voltge Read back Field.vi”

Simultaneously controls the Keithley 213 Quad Voltage Source and reads back field readings from the Group 3 Digital Teslameter.

The control, “Control Voltage”, changes the output voltage of the voltage source (see figure 11).

A round indicator button turns black when the measured field has become constant.

A second after the constant field indicator turns black the program quits.

“Temperature controller.vi”

This program controls the Oxford ITC4 Temperature controller and no other instrument. The controls presented on the screen of this vi are somewhat more complex than those of the other instrument vi’s (see figure 12).

The “Maximum Heater Voltage” control and the controls for the PID parameters can be set and read back during operation.

The control “Heater Control Sensor” is available for selecting one of three sensor ports for temperature control/measurement.

The “Set Temperature” control is used to change and read back the ITC4’s target temperature.

The indicator “Sensor _ Temperature” displays at regular set intervals the temperature recorded by the ITC4.

The control “Time between measurements” sets the timing at which the program reads a measurement from the ITC4 Temperature Controller.

The “Acceptable Error” control is used together with the “Time between measurements” control to set the conditions for which the program determines that temperature stabilization has occured. When temperature stabilization has occured the oval shaped indicator turns black and shortly after that the program quits.

Temperature stabilization is determined to occur as follows. The program, at periods determined by the “Time between measurements” control, continually updates and saves the last twenty measurements in a program buffer. The “Set Temperature” is subtracted from each of these twenty measurements during each measurement cycle resulting in twenty consecutive error measurements. Stabilization occurs when the maximum of these twenty error measurements is less than the “Acceptable error”.

“Two smus operation.vi”

Provides for the simultaneous control of two Keithley 236 Source Measure Units (SMUs).

“Two smus operation.vi “ allows a user to create SMU configuration files which can be saved and recalled. The SMU configuration files created by “Two smus operation.vi” can also be used by “Combined Control.vi”. User is prompted to give configuration file a name when saving.

“Two smus operation.vi” runs the SMUs in a three terminal, family of curves mode. At the completion of a sweep the acquired data is graphically displayed on the monitor.

Program allows user to save sweep run data to a comma delimited spreadsheet file. User is prompted by program to give the spread sheet file a name.

End of document.

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