Using Instrument Drivers - C

NI-VISA Measurement & Automation

Using instrument drivers (in C)

You can use VXIplug&play instrument drivers under Windows in the following supported C compilers: LabWindows/CVI, Microsoft Visual C++, and Borland C++.

The distribution disk of a WIN framework instrument driver contains the C source code files (.C and .H), a function panel file (.FP) that describes the graphical panels associated with the instrument driver, a DLL file (.DLL) which is a compiled version of the driver, and a Windows help file (.HLP).

To use the functions of the instrument driver, you must include the .H file in your C code. Unless you are using LabWindows/CVI, you need to link in the compiler-specific import library (.LIB) file to your project and copy the .DLL file to the Windows/System or WinNT/System directory.

Your program's first task is to initialize the connection to the instrument by calling the INITIALIZE function. One of the outputs of the INITIALIZE function is an Instrument ID, which is essentially a handle to the instrument. Once you have initialized your instrument connection, you can then either use the high-level APPLICATION functions, which perform complete measurement operations, or the lower-level COMPONENT functions, which give you more granularity in controlling the instrument's operation. At the end of your program, you should use the CLOSE function to close the connection to the instrument.

An important feature to take advantage of when using your VXIplug&play instrument driver is the online help included with the driver. The help describes each component of the driver and shows a hierarchical outline of its components.