Basler A640F, User Manual

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Smart Features
BASLER A640
f
6-7
DRAFT
6.6 Getting Smart Features Results
In many cases, activating a smart feature results in additional data that must be transmitted by the
camera, i.e., the results of the smart feature. The results of a smart feature will be appended to
the image data so that each frame contains both image data and smart features results.
Before using any of the smart features that add information to the image data, the extended data
stream feature must be enabled. The extended data stream is in itself a smart feature. When the
extended data stream feature is enabled, information such as the height of the image, the width
of the image, and the AOI size is added to each image’s basic pixel data. Disabling the extended
data stream feature switches off all smart features that add information to the image data stream.
The extended data stream feature and any other smart features which add information to the
image data stream will only work when the camera is set for video format 7. For other video
formats, enabling the extended data stream feature or any of the other smart features that
normally add data to the image stream does not affect the image data stream; the camera only
sends the basic image data without any added information.
Figure 6-1: Image Data Stream with Smart Features Enabled
As illustrated in Figure 6-1, when smart features are enabled, each image frame consists of
“chunks.” For example, the frame may include a chunk which contains the extended image data
(the basic image data plus the added height, width, etc. information), a chunk which contains the
results for the frame counter smart feature, a chunk which contains the results for the cycle time
stamp smart feature, etc. Table 6-1 describes the general structure of a chunk.
Each chunk ends with a four byte unsigned integer indicating the length of the chunk and four
bytes which indicate the bitwise complement of the length. Transferring both the chunk length and
the bitwise complement of the length serves as a mechanism to detect transmission errors. If the
last four bytes of a chunk aren’t the bitwise complement of the preceding four bytes, the chunk’s
length information isn’t valid and this indicates that a transmission error occurred.
Position Name Description
0 Data
[ K Bytes ]
The data that the chunk is transporting.
K Chunk GUID
[ 16 Bytes ]
Identifies the type of chunk and the smart feature associated with the
chunk. (Note that a smart feature’s chuck GUID is not the same as
its CSR GUID.)
K+16 Length
[ 4 Bytes ]
The chunk’s total length in bytes.
K+20 Inverted Length
[ 4 Bytes ]
The bitwise complement of the length.
Table 6-1: General Structure of a Chunk