National Instruments Image Acquisition Software User Manual

Also see for NI-IMAQ: User manual

Contents

National Instruments Image Acquisition Software User Manual Manual pdf 21 page image

©National Instruments Corporation3-1NI-IMAQ User Manual3Programming with NI-IMAQThis chapter contains an overview of the NI-IMAQ library, a descriptionof the programming flow of NI-IMAQ, and programming examples.Flowcharts are included for the following operations: snap, grab, sequence,ring, and StillColor acquisitions.IntroductionThe NI-IMAQ API is divided into two groups, the high-level functionsand the low-level functions. With the high-level functions, you can writeprograms quickly without having to learn the details of the low-level APIand driver. The low-level functions give you finer granularity and controlover your image acquisition process, but you must understand the API anddriver in greater detail.Note The high-level functions call low-level functions and use certain attributes thatare listed in the high-level function description in the NI-IMAQ FunctionReference Manual. Changing the value of these attributes while using low-levelfunctions will affect the operation of the high-level functions.High-Level FunctionsThe 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; youobtain a copy of the acquisition buffer by grabbing a copy to a separatebuffer that can be used for analysis.• Sequence performs an acquisition that acquires a specified number ofbuffers, then stops.• Ring performs an acquisition that loops continually on a specifiednumber of buffers.The high-level function set also allows simple triggered acquisitions andthe generation of external signals on the trigger lines.