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Device number

In addition to the data format, MdigAlloc() requires that you specify the number or string to identify the acquisition path(s) to allocate for a digitzer. Typically, only one acquisition path is required to grab from a camera. Note that a connection to a network camera is considered an acquisition path.

Typically, each acquisition path can only be associated with one digitizer at a time. In these cases, if the specified acquisition path is not available, (for example, because no camera is connected, or because the acquisition path is already allocated), the allocation fails and an error is generated. Note that some older frame grabbers did not have this restriction and would perform grabs from these digitizers sequentially.

Using a frame grabber

When using a camera connected to a frame grabber, you use the device number to identify which acquisition path(s) on the frame grabber to allocate for the digitizer. Typically, this corresponds to the index of the connector on the frame grabber.

For a CXP camera that uses multiple connections, you set the device number of the digitizer to the index of the connector used for the master connection. The other connections (acquisition paths) used for the camera are associated with the digitizer automatically.

Using a network camera

When using a network camera (for example, allocated on a MIL GigE Vision system), you can use an IP address, camera name, or device number (the camera's rank, determined when MIL enumerates the cameras that are visible from the operating system of your computer) to identify the camera to allocate for the digitizer. Each network camera uses one acquisition path, with a total of 32 acquisition paths being available per interface board.

All network cameras can transmit data to the Host independently of each other. Therefore, each network camera uses an independent acquisition path. However, completion of a grab from a network camera might be delayed due to the bandwidth limitations of your network, packet size limitations, and/or firewall restrictions.

Using a Matrox Iris smart camera

For a Matrox Iris smart camera, the device number is always 0.