Measurement Computing WaveBook rev.3.0 - Manual (Page 175)

WaveBook User’s Manual, 6-22-99 daqX API - Programming Models C-1
daqX API - Programming Models Appendix C
Introduction…… C-1
Data Acquisition Environment…… C-1
Application Program Interface (API)…… C-1
Enhanced vs Standard API…… C-2
Hardware Capabilities & Constraints…… C-2
Signal Environment…… C-2
Basic Models…… C-2
Initialization & Error Handling…… C-3
Foreground Acquisition with One-Step Commands…… C-4
Counted Acquisitions Using Linear Buffers…… C-6
Indefinite Acquisition, Direct-To-Disk Using Circular Buffers…… C-8
Multiple Hardware Scans, Software Triggering…… C-10
Background Acquisition…… C-12
Complex Triggering…… C-13
Data Packing & Rotating…… C-15
Direct-To-Disk Transfers…… C-17
Transfers with Driver-Allocated Buffers…… C-20
Summary Guide of Selected API Functions…… C-22
Introduction
The Enhanced API allows you to create custom software to satisfy your WaveBook data acquisition
requirements. Appendices C and D provide the basic concepts and details to write effective programs.
Appendix D describes the API functions in detail.
Appendix C is divided into 3 parts:
• Data Acquisition Environment outlines related concepts and defines system capabilities the
programmer must work with (the API, hardware features, and signal management).
• Programming Models explains the sequence and type of operations necessary for data acquisition.
These models provide the software building blocks to develop more complex and specialized
programs. The description for each model has a flowchart and example program excerpt.
• Summary Guide of Selected API Functions is an easy-to-read table that describes when to use the
basic API functions.
Note: The WaveBook Enhanced API is a subset of the DaqX Enhanced API which provides a common
interface for 32-bit data acquisition applications (WaveBook, DaqBook, DaqBoard, Daq PC-Card,
TempBook, etc). Hence, the term Daq* can apply to devices other than WaveBooks and WBKs.
However, this manual describes only the commands that pertain to the WaveBook.
Data Acquisition Environment
In order to write effective data acquisition software, programmers must understand:
• Software tools (the API documented in this manual and your programming language—you may need to
consult documentation for your chosen language).
• Hardware capabilities and constraints.
• General concepts of data acquisition and signal management.
Application Program Interface (API)
The API includes all the software functions needed for building a data acquisition system with the hardware
described in this manual. Appendix D: daqX API - Command Reference supplies the details about how
each function is used (parameters, hardware applicability, etc). In addition, you may need to consult your
language and computer documentation.