Smart Features6-8 BASLER A102fDRAFTThere are different types of chunks, for example, the chunk that is added when the cycle timestamp smart feature is enabled and the chunk that is added when the frame counter smart featureis enabled. Although most chunks follow the general structure described in Table 6-1, each typeof chunk has unique aspects to its layout. To allow you to distinguish between the chunks, eachchunk carries a “chunk GUID”. The GUID for each chunk is transferred just before the chunk’slength information. If you look through the descriptions of the smart features in Section 6.7, youwill notice that for smart features which add a chunk to the image data stream, there is adescription of the layout of the chunk and the chunk GUID associated with the chunk.A chunk’s length field contains the chunk’s total length in bytes. The GUID, the length, and theinverted length are included as part of the total chunk length.By appending length information and a chunk GUID to each chunk, the camera sends a self-describing data stream and allows easy navigation through the individual chunks that make up acomplete image data frame.6.6.1 How Big a Buffer Do I Need?When smart features that add data to the image are enabled, the size of each transmitted framewill be larger than you would normally expect for a frame which contains only image data. Todetermine the size of the buffer that you will need to hold an image with appended smart featuresdata, check the Total Bytes High Inquiry and Total Bytes Low Inquiry registers of the Format 7mode you are currently using. Make sure to check these registers after all smart features havebeen enabled and all other settings affecting the image size have been completed. The sizeinformation in these fields will allow you to properly set up buffers to receive the transmittedimages.L Don’t confuse CSR GUIDs with chunk GUIDs:• Each smart feature has a control and status register (CSR) associated with it andeach CSR has a unique “CSR GUID” assigned to the register. The CSR GUIDsare used to help you keep track of which CSR is associated with each smart fea-ture.• Any smart feature that adds a “chunk” of data to the image data stream also hasa unique “chunk GUID” assigned to the feature. The chunk GUID will be includedthe chunk of data that a smart feature adds to the image data. The chunk GUIDslet you determine which smart feature is associated with each added chunk inthe image data stream.L The CRC Checksum is an exception to the general structure of a chunk. See Section6.7.5 for more information.
