National Instruments 320685D-01 Advantages and Disadvantages of Using Loadable Compiled Modules inLabWindows/CVI , Using a Loadable Compiled Module as an Instrument Driver ProgramFile

Chapter 2 Using Loadable Compiled Modules

LabWindows/CVI Programmer Reference Manual 2-2

National Instruments Corporation

Advantages and Disadvantages of Using Loadable Compiled Modules inLabWindows/CVI

Using compiled modules in LabWindows/CVI has the following advantages:

• Compiled modules run faster than source modules. Compiled modules do not contain the

debugging and user protection code LabWindows/CVI generates when it compiles

source modules. Compiled modules you generate in external compilers can run faster

because of optimization.

• LabWindows/CVI recompiles the source modules in a project each time you open the

project. Also, if an instrument driver program file is a source module, LabWindows/CVI

recompiles it each time you load the instrument driver. LabWindows/CVI does not

recompile compiled modules when you open a project or load an instrument driver.

• In standalone executables, you can dynamically load compiled modules but not source

modules.

• You can install compiled modules, but not source modules, into the Library menu.

• You can provide libraries for other developers without giving them access to your source

code.

Using compiled modules in LabWindows/CVI has the following disadvantages:

• You cannot debug compiled modules. Because compiled modules do not contain any

debugging information, you cannot set breakpoints or view variable values.

• Compiled modules do not include run-time error checking or user protection.

Using a Loadable Compiled Module as an Instrument Driver ProgramFile

An instrument driver is a set of high-level functions with graphical function panels to make

programming easier. It encapsulates many low-level operations, such as data formatting and

GPIB, RS-232, and VXI communication, into intuitive, high-level functions. An instrument

driver usually controls a physical instrument, but it also can be a software utility. The Using

Instrument Drivers and Instrument Menu sections of Chapter 3, Project Window, of the

LabWindows/CVI User Manual describe how to use instrument drivers.

To develop and debug an instrument driver, load its program file into LabWindows/CVI as a

source file. After you finish debugging it, you can compile the program file into an object file

or a Windows 95/NT DLL. The next time you load the instrument driver, LabWindows/CVI

loads the compiled module, which loads and runs faster that the source module.

Refer to the LabWindows/CVI Instrument Driver Developers Guide for information on how

to create an instrument driver.