Device number
In addition to the data format, MdigAlloc() requires that you specifies the number or string to identify the device to allocate for the digitizer. When using a frame grabber, its digitizer configuration format (DCF) establishes the total number of acquisition paths used. MIL associates a timing control unit (for example, a PSG) on your frame grabber, with these acquisition paths when grabbing. If a timing control unit or the specified acquisition paths are not available when a grab is requested, the grab request must wait until they become available.
Using a frame grabber
When the Matrox frame grabber has only one timing control unit, you must specify M_DEV0 or M_DEFAULT as the device number for the digitizer, regardless of the number of acquisition paths available.
If a digitizer can grab while another digitizer on the same frame grabber is simultaneously grabbing, it is said to be independent. If it cannot, it is dependent. The maximum number of digitizers from which you can grab simultaneously equals the number of timing control units on your Matrox frame grabber.
In order for the two digitizers depicted below to grab simultaneously, there must be at least two timing control units on your Matrox frame grabber. In the following image, the first camera is a component RGB camera and the second one is a monochrome camera. They are connected to their associated acquisition paths on a frame grabber.
For more information regarding the number of available timing control units, refer to the Installation and Hardware Reference manual and the MIL Hardware-specific Notes for your Matrox frame grabber.
Using a network camera
When using one or more network cameras (for example, a MIL GigE Vision system), a device number, IP address, or camera name can be used to identify the camera to allocate for the digitizer. Each network camera is said to use one acquisition path, with a total of 32 acquisition paths being available per interface board. All digitizers representing network cameras that are visible from the operating system of your computer, can simultaneously grab and therefore each digitizer (network camera) is independent. However, completed grabs might be delayed due to the bandwidth limitations of your network, packet size limitations, and/or firewall restrictions.