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National Instruments Corporation 1-1 NI-DAQ FRM for PC Compatibles
Chapter
1
Using the NI-DAQ Functions
This chapter contains important information about how to apply the
function descriptions in this manual to your programming language and
environment.
When you are familiar with the material in the NI-DAQ User Manual for
PC Compatibles, you can use this manual for detailed information about
each NI-DAQ function.
Status Codes, Device Numbers, and SCXI Chassis IDs
Every NI-DAQ function is of the following form:
status
=
Function_Name (parameter 1, parameter 2, … parameter n)
where n ≥ 0. Each function returns a value in the
status
variable that
indicates the success or failure of the function, as shown in Table 1-1.
Note
In all applications,
status
is always a 16-bit integer. Appendix A,
Status Codes
,
contains a list of
status
codes.
In the parameter tables that follow the status codes, the first parameter to
almost every NI-DAQ function is the device number of the DAQ device you
want NI-DAQ to use for the given operation. After you have followed the
installation and configuration instructions in the NI-DAQ release notes and
Chapter 1, Introduction to NI-DAQ, of the NI-DAQ User Manual for PC
Compatibles, you can use the NI-DAQ Configuration Utility to determine
the device number for each device you have installed in the system.You can
Table 1-1.
Status Values
Status Result
Negative Function did not execute because of an error
Zero Function completed successfully
Positive Function executed but with a potentially serious
side effect