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LDC 3744B - OMM 6810B - TDS 210
LabVIEW 5.1SOFTWARE
Microphotonics Research LaboratoryKoç University Physics Department
Rumeli Feneri Yolu, Science Building, Room 147 Sariyer, Istanbul 34450 Turkey Credits: Şenol İşçi
TABLE OF CONTENTS
1. Introduction 3
2. Installation 3
2.1. Checking System Requirement 3
2.1.1. Requirements for the Hardware 3
2.1.2. Requirements for the Software 4
2.2. Installing the LDC&OMM&TDS System 4
2.3. Installing the Software 4
3. Getting Started 5
3.1. Using the Mouse and Drop-down Menu 5
3.1.1. The Mouse 5
3.1.2. The Drop-down Menu
6
3.2. Menus, Tool Bar, Controls and Indicators
6
3.2.1. Menus
6
3.2.1.1. File Menu 6
3.2.1.2. Edit Menu 7
3.2.1.3. Operate Menu
7
3.2.1.4. Windows Menu 7
3.2.1.5. Help Menu 7
3.2.2. Toolbar 7
3.2.2.1. Description 7
3.2.2.2. Running VI 8
4. LDC_OMM_TDS_MAIN.vi 8
4.1. User Interface
9
APPENDIX 1 GPIB 14
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APPENDIX 2 VISA 15
CONTACT INFORMATION 16
1. Introduction
The LDC&OMM&TDS software provides an interface between a laser
diode controller, an optical multimeter and a digital oscilloscope. The
LDC&OMM&TDS system consists of an ILX Lightwave LDC 3744B Laser Diode
Controller, an ILX Lightwave OMM 6810B Optical Multimeter, and a Tektronix
TDS 210 Digital Oscilloscope.
The software was written mainly in LabVIEW version 5.1 for Windows.
Most of the sub VIs’ utilized were from the device manufacturers’ software
resources. For fastest image display and image quality, it is recommended
that you have a minimum of 32MB of RAM and a monitor resolution of
1024x768 pixels.
2. Installation
Refer to the ILX LDC, ILX OMM and TektronixTDS user manuals for
proper power and communications, as well as any other pertinent installation
information. All devices have GPIB interfaces, which are IEEE 488.2-
compatible (see Appendix 1 for further information).
2.1. Checking System Requirement
Check to make sure that your computer meets the minimum
requirements for the LDC&OMM&TDS system.
2.1.1. Requirements for the Hardware
A Personal Computer
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PCI-GPIB Board
High-quality shielded GPIB cabling to meet your system needs
A mouse or any other pointing device.
A VGA, SVGA display, or 1024x768.
Minimum of 32 MB of RAM recommended.
2.1.2. Requirements for the Software
Any IBM compatible machine with an 80386 processor or higher.
A hard disk with at least 10MB free space, and 7MB is needed for
installation.
Microsoft Windows 95 or newer in standard or enhanced mode.
2.2. Installing the LDC&OMM&TDS System
Before making any connections between a computer to the LDC, OMM,
and TDS, all of the devices should be off.
Connect all devices to the PC with GPIB cables.
The GPIB address (software default) for LDC is 1.
The GPIB address (software default) for TDS is 2.
The GPIB address (software default) for OMM is 3.
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Connect all devices’ power cables.
For detailed description of hardware installations and cable connections,
please refer to the manufacturers’ user manuals.
2.3. Installing the Software
1. Open “LDC_OMM_TDS.LLB”, which is a Labview library file.
2. Select the LDC_OMM_TDS_MAIN.VI, which is the application software
for the LDC 3744B OMM 6810B TDS 210 system.
3. Getting Started
Once the “LDC_OMM_TDS_MAIN.VI” has been opened, you are ready to
get started.
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Library Files
3.1. Using the Mouse and Drop-down Menu
3.1.1. The Mouse
The mechanics of using a mouse with the software conforms to the
Microsoft Windows standard. The following conventions are used in the
manual when explaining manipulations with the mouse: “Clicking” the mouse
on an object consists of moving the mouse cursor until it is pointing to the
object and depressing the specified mouse button once or twice in quick
succession. If you have reconfigured your mouse for other-handed use,
switch the references (specified or assumed) to the right and left buttons.
3.1.2. The Drop-down Menu
Menu options are referenced as “to level menu”: “submenu option”
like these following examples:
File
Open… is referenced as File:Open…
Help
Show Help is referenced as Help: Show Help
3.2. Menus, Tool Bar, Controls and Indicators
This section has detailed descriptions about the menus, tool bar,
controls and indicators. For each menu, a brief description of each command
is given. In addition, LabVIEW programs are called virtual instruments (VIs).
3.2.1. Menus
3.2.1.1. File Menu
Open. Opens an existing VI. A status dialog is displayed while that VI is
opening. This status dialog identifies the VIs that are currently being
loaded and gives you an opportunity to cancel the load process.
Close. Closes the active window and does not save any changes you have
made.
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Printer Setup… Sets configuration options for the printer. You can
change the orientation of printout (landscape versus portrait). Printer
Setup settings are saved with your VI.
Print Window… Prints out the contents of the currently active window.
Using this option, you can make a quick printout with the minimum
number of prompts.
Exit. Quit LabVIEW.
3.2.1.2. Edit Menu
Preferences… Sets preferences for memory, disk, and display.
3.2.1.3. Operate Menu
Run. Executes the current VI.
Print at Completion. Prints the contents of a VI’s front panel after each
execution.
Log at Completion. Logs a time stamp and the data in all front panel
controls of a VI to a separate datalog file.
Data Logging. Displays data logging options. (Optional if you have
LabVIEW software).
Reinitialize All to Default. Sets all controls and indicators to their
default values.
3.2.1.4. Windows Menu
Show VI Info... Displays the VI file path, revision number, and memory
usage.
Show Clipboard. Displays the contents of the clipboard.
Full Size. Uses the entire screen to display the active window.
3.2.1.5. Help Menu
Show Help. Is a Context-sensitive Help window that displays a function’s
or VI’s parameters, parameter type definitions, and the description for
the object.
About. Information on LabVIEW software version number and serial
number.
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3.2.2. Toolbar
3.2.2.1. Description
The LabVIEW toolbar contains four command buttons as in figure 1.
Fig. 1. LabVIEW Toolbar
Run button. Runs the VI.
Continuous run button. Runs the VI over and over.
Stop button. Aborts VI execution.
Pause/Continue button. Pauses VI execution/Continue VI execution.
3.2.2.2. Running VI
You can run a VI by selecting Operate: Run or clicking on the run
button.
While the VI is executing, the run button changes appearance. If the VI
is running at its top level, the run button looks like the illustration
shown to the left.
If the VI is executing as a sub VI, the run button changes to look like
the illustration shown to the left.
4. LDC_OMM_TDS_MAIN.vi
The application gets spectral data by tuning the temperature via LDC at
constant current mode.
The system designed upon VISA (see Appendix 2 for further information) is a
standard I/O Application Programming Interface (API) for instrumentation
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programming. Our GPIB system uses a single GPIB interface to communicate
with several GPIB instruments. Each instrument is configured to use a
different primary address. The GPIB controller (Our Personal Computer)
acquires and displays a fixed number of readings from each instrument. The
Programming is based on Single-Threaded Solution. In the single-threaded
solution, our application does the following:
1) Set the control parameters for LDC TEC and LAS operations.
2) Set the TDS reading to “Mean” measurement and acqusition channel
(software default for measurement channel is Channel1)
3) Initialize the OMM.
4) Go to starting Temperature value
5) Scan temperature up till the stop temperature point is reached.
6) While more readings to acquire
a. Tell LDC to send data
b. Acquire data from LDC
c. Tell TDS to send data
d. Acquire data from TDS
e. Tell OMM to send data
f. Acquire data from OMM
g. Display acquired data
7) Save data to the specified folder
4.1. User Interface
The interface is mainly composed of LDC parameter controls and status
displays for various settings of LDC, OMM and TDS. The graphs display the
acquired data.
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Status Display and Stop Button
During the operation, you will see the actions of the Application Software and
be notified in case of error.
Stop Button stops the Scan Procedure and allow saving data before
completely finishing execution.
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LDC Settings
Set Point (mA) : LDC can operate at
constant power or constant current
mode. In our application, Constant
mode is selected as the software
default. Set Point (mA) will set the LDC
to Constant Current Low bandwidth
mode.
tempset_start is the starting scan
temperature value
tempset_stop is the stopping scan
temperature value
Temperature Limit set the maximum
temperature The LDC will allow before
generating an action. During controller
operation, is this limit is reached, The
Laser and TEC output will be shut off to
protect the laser.
TEC Current Limit Function limits the controller’s output current so that
the instrument does not provide more current than your TE module can
safely handle.
Temperature Conversion Constants:
These sensor calibration constants are necessary for accurate conversion to
actual temperature. Please refer to whitepaper of your thermistor used in
LDC for necesaary information.
GAIN is the TE control loop gain. The GAIN function sets the analog feedback
gain, which in part, determines how fast the actual temperature reaches and
settles to the setpoint temperature.
In LDC&OMM&TDS software, during the scan, the TE current
limit is continuously increased at number of data point taken
determined by TElim Update at TE lim step rates. This
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method allows increase in the number of readings from the system. For
different laser diodes, User can run the application for several update
parameter schemes in order to get the best setting.
Update Parameters toggle switch updates
the LDC control parameters above
Las Output LED button will be on when the current source output
of the laser diode is enabled.
TEC Output LED butoon will be illuminated when the TE control
loop is enabled.
This Function allows immediate temperature
setpoint update.
These displays are the data acquired
from the system after scanning.
folder specifies the path, in which the readings will be saved.
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Oscilloscope is data coming from TDS. Unit,
Source and Type are the parameters set for TDS.
Temperature(C) is the current temperature limit
display. TEC Current (A) display is updated during
the scan. GAIN and the C1,C2,C3 indicators show
the current values set.
Power and wavelength measurements are
acquired from OMM.
Temperature Graph displays the temperature values during scanning. X-axis
is the number of data taken. This graph is hany when the user arranges the
scan settings such as TE lim start, TE lim Update mentioned above.
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Scope graph displays the data acquired from the TDS
This graph displays the TDS reading as a function of Temperature. It will
show up at the end of scan process.
APPENDIX 1
GPIB (General Purpose Interface Bus)
Often referred to as the IEEE-488.2 bus, GPIB bus or HP-IB bus, the GPIB
(General Purpose Interface Bus) is a standard for instrumentation
communication and control for instruments from manufactures the world
over. In 1965, Hewlett-Packard designed the Hewlett-Packard Interface Bus
(HP-IB) to connect their line of programmable instruments to their
computers. Because of its high transfer rates (nominally 1 Mbytes/s), this
interface bus quickly gained popularity. It was later accepted as IEEE
Standard 488-1975, and has evolved to ANSI/IEEE Standard 488.1-1987.
Today, the name General Purpose Interface Bus (GPIB) is more widely used
than HP-IB. ANSI/IEEE 488.2-1987 strengthened the original standard by
defining precisely how controllers and instruments communicate. Standard
Commands for Programmable Instruments (SCPI) took the command
structures defined in IEEE 488.2 and created a single, comprehensive
programming command set that is used with any SCPI instrument.
The GPIB provides handshaking and interface communications over an 8 bit
data bus employing 5 control and 3 handshake signals.
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Equipped with a PCI-GPIB, a personal computer can:
Control GPIB instruments.
Gather data from GPIB test equipment.
Become a data acquisition station in a GPIB system.
APPENDIX 2
VISA
VISA is a standard I/O Application Programming Interface (API) for
instrumentation programming. VISA by itself does not provide
instrumentation programming capability. VISA is a high-level API that calls
into lower level drivers. The hierarchy of NI-VISA is shown in the figure below.
VISA can control VXI, GPIB, or serial instruments, making the appropriate
driver calls depending on the type of instrument being used. When
debugging VISA problems it is important to keep in mind that this hierarchy
exists.
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GPIB interfacing
VISA Is the Standard
VISA is the standard API for instrument drivers throughout the
instrumentation industry. In addition, you can use one API to control a suite
of instruments of different types, including VXI, GPIB and serial.
Interface Independence
VISA uses the same operations to communicate with instruments regardless
of the interface type. For example, the VISA command to write an ASCII
string to a message-based instrument is the same whether the instrument is
serial, GPIB, or VXI. Thus VISA provides interface independence. This makes
it easier to switch bus interfaces, which means that users who must program
instruments for different interfaces only need to learn one API.
Platform Independence
VISA is designed so that programs written using VISA function calls are easily
portable from one platform to another. To ensure platform independence,
VISA strictly defines its own data types. Therefore issues like the size, in
bytes, of an integer variable from one platform to another should not affect a
VISA program. The VISA function calls and their associated parameters are
uniform across all platforms. Software can be ported to other platforms and
then recompiled. A LabVIEW program can be ported to any platform
supporting LabVIEW.
Easily Adapted to the Future
Another advantage of VISA is that it is an object-oriented API that will easily
adapt to new instrumentation interfaces as they are developed in the future,
making application migration to the new interfaces easy.
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For Further Information, Please Contact:
Şenol İşçi :
E-mail: [email protected]
Microphotonics Research Laboratory
Koç University Physics Department
Rumeli Feneri Yolu, Science Building, Room 147 Sariyer, Istanbul 34450
Turkey
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