Programming With Ni-Imaq; Introduction; High-Level Functions - National Instruments Image Acquisition Software User Manual

Programming with NI-IMAQ

Introduction

Note The high-level functions call low-level functions and use certain attributes that
are listed in the high-level function description in the NI-IMAQ Function
Reference Manual. Changing the value of these attributes while using low-level
functions will affect the operation of the high-level functions.

High-Level Functions

© National Instruments Corporation
This chapter contains an overview of the NI-IMAQ library, a description
of the programming flow of NI-IMAQ, and programming examples.
Flowcharts are included for the following operations: snap, grab, sequence,
ring, and StillColor acquisitions.
The NI-IMAQ API is divided into two groups, the high-level functions
and the low-level functions. With the high-level functions, you can write
programs quickly without having to learn the details of the low-level API
and driver. The low-level functions give you finer granularity and control
over your image acquisition process, but you must understand the API and
driver in greater detail.
The high-level function set supports four basic types of image acquisition:
• Snap acquires a single frame or field to a buffer.
• Grab performs an acquisition that loops continually on one buffer; you
obtain a copy of the acquisition buffer by grabbing a copy to a separate
buffer that can be used for analysis.
• Sequence performs an acquisition that acquires a specified number of
buffers, then stops.
• Ring performs an acquisition that loops continually on a specified
number of buffers.
The high-level function set also allows simple triggered acquisitions and
the generation of external signals on the trigger lines.
3-1
3
NI-IMAQ User Manual