This function puts a specified descriptor in focus and sets its update state.


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Controls and Indicators


         hCamera IN is the camera handle. This value is returned by Initialize.vi and is passed between PixeLINK VIs as a reference.


           hDescriptorHandle IN is the handle of the descriptor. This value is returned by the CreateDescriptor VI. Set to 0 to select all descriptors.


           uUpdateMode IN is an enumerated control which sets the descriptor update mode to Camera or Host.


           hCamera OUT has the same value as hCamera IN.


           hDescriptorHandle OUT has the same value as hDescriptorHandle IN.


           uUpdateMode OUT has the same value as uUpdateMode IN.



Details


A descriptor is applicable only to the camera for which it was created.


The specified descriptor is in focus (that is, its settings can be changed using SetFeature, or read using GetFeature), until one of the following occurs:



  • another descriptor is brought in focus using UpdateDescriptor, or


  • the descriptor is deleted using RemoveDescriptor, in which case the focus reverts to the first descriptor created.


When a descriptor exists and is in focus, all calls of GetFeature and SetFeature refer to the settings of that descriptor.


All descriptors may be brought in focus simultaneously by setting hDescriptorHandle IN to 0. Otherwise, only one descriptor may be in focus at a time. Note that if all descriptors are in focus at once (rather than just a single descriptor), calling GetFeature will generate an error.


If uUpdateMode IN is set to PXL_UPDATE_HOST, then the descriptor is updated on the host computer only. Changes will not be applied to the camera until UpdateDescriptor is called for that descriptor with uUpdateMode IN set to PXL_UPDATE_CAMERA.


If uUpdateMode IN is set to PXL_UPDATE_CAMERA, then the descriptor is updated on the host computer and changes are applied immediately to the camera.


If the descriptor update mode was originally set to PXL_UPDATE_HOST and uUpdateMode IN is set to PXL_UPDATE_CAMERA, the descriptor is transferred to the camera and all the changes to settings are applied at once.


For best performance, update the descriptor settings in PXL_UPDATE_HOST mode, then call UpdateDescriptor with uUpdateMode IN set to PXL_UPDATE_CAMERA to apply all changes to the camera settings at once. After this is done, return the descriptor to host mode by calling UpdateDescriptor with uUpdateMode IN set to PXL_UPDATE_HOST.


Note: See Error Handling for error input and output information and error codes.