Data Translation DT3152-LS, User Manual

Page: 64 / 214

Chapter 2
48
Line-Scan Operations
For line-scan operations, the DT3152-LS board supports
asynchronous, continuous-acquire passthru mode. Since it is
asynchronous, the operation starts and then returns control to you
immediately, allowing you to perform other operations while data is
acquired and/or displayed.
Using software, you can set up the continuous-acquire passthru
operation so that data is continuously displayed but not stored (in
this mode, the board behaves like asynchronous bitmap passthru
mode), continuously stored but not displayed, or continuously
displayed and stored.
If you want to display data in continuous-acquire passthru mode,
functions in Windows perform bit copies of the image data to display
memory. These functions also handle obstructions to the passthru
window by automatically clipping the passthru image to the visible
client window region. Therefore, even if the window is obstructed in
bitmap mode, the passthru can continue unabated. Once an
obstruction has been removed from the passthru window client area,
Windows automatically restores the correct underlying image data.
Continuous-acquire passthru mode requires user buffers in host
memory only if you want to store the passthru data. If you want to
display the data only, you do not need any user buffers. Refer to
Appendix D for more information on allocating and handling user
buffers for continuous-acquire passthru operations.
Continuous-acquire passthru mode also has a synchronization
mechanism using a WIN32 event object. Using this object, you can
synchronize your application with the DT3152-LS board to process
data as it becomes available.
The continuous-acquire passthru operation continues until the user
buffers are filled or until you stop the operation using software (in
this case, the user buffers are overwritten).