# Cameras and ToolBlocks

When your VisionPro application launches, the software automatically generates a list of all connected GigE Vision cameras. The list orders cameras by their IP addresses that you set with the GigE Vision Configuration utility.

For each ToolBlock you add to a multi-camera application, you must associate it with one GigE Vision camera from the list. As your application executes, each ToolBlock acquires images only from its assigned camera. So long as all cameras are connected and powered on when the application launches, each ToolBlock has a reliable image source.

In some production environments, you might want to use an existing multi-camera application in a single-camera environment. For example, the following figure shows the previous application being used only to read barcode symbols with ToolBlock 2, while there is no camera necessary to supply images to ToolBlock 1:

As VisionPro enumerates all connected cameras at startup, the association of cameras to ToolBlocks can become corrupted should any expected cameras be missing. For example, if a camera assigned to ToolBlock 1 is not present when the application is launched, ToolBlock 1 is assigned the next available camera in the list. In a two-camera application, this can mean the camera previously assigned to ToolBlock 2 is assigned to ToolBlock 1 and neither ToolBlock receives the expected image:

With PCE enabled, this application would get a virtual camera assigned to ToolBlock 1 and ensure the application supplies ToolBlock 2 with the image from the correct camera: