Advantech AIIS-1882, Руководство пользователя

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AIIS-1882 User Manual 18
In SDK programming reference, the corresponded parameters could also be found.
The prototype of PWM high/low argument structure declaration could be found in
C:\Advantech\DAQNavi\Inc\bdaqctrl.h. (In this manual, we take C++ as programming
example for guidance. Other programming languages follow the same concept and
programming style.)
The APIs setting the PWM properties could also be found in
bdaqctrl.h
by searching
for the class
PoChannel
.
Figure 3.11 Class PoChannel in bdaqctrl.h
For the setting of parameters, the programming example Counter_PWMOutput
describes the details (C:\Advantech\DAQNavi\Examples).
3.3.1 Infinite lighting output
To set the infinite lighting output, it’s suggested to set the frequency of output much
larger (10~100x) than the camera frame rate, so that the PWM output could evenly
distributed within the camera exposure period. For example, the maximum frame rate
of the camera is 500fps, it means the exposure period is 2ms, so for the PWM period
we suggest at least 0.2ms. As a result, the high and low periods should be set within
0.2ms, using duty-cycle to set the lighting intensity. Below is the result of setting dif -
ferent PWM output parameters with different cameras, using different configurations.
In this mode, the output count should be set to 0, which stands for infinite PWM out -
put count. The table below describes the relationship between High/Low period set -
tings and the result intensity percentage for the given camera frame rate.
typedef struct
PulseWidth {
double
HiPeriod;
double
LoPeriod;
} PulseWidth;