Non-Genlocked (Free-run): (IMAQ PCI/PXI 1408, IMAQ PCI/PXI 1409)
Use this mode to connect multiple cameras to one image acquisition device without synchronizing them to each other (without genlocking or asynchronous resetting). When the trigger is received for a particular channel, the board will acquire the next full frame from the desired channel. The image acquisition device will have to resynchronize to the next camera signal, which will add an additional amount of time delay in order to synchronize to that camera's timing signals. If the camera is in the middle of a frame, then the image acquisition device will wait for the next frame before acquiring the image. This is a good solution for capturing images that are not time sensitive. If the object is moving or the event is time-critical, this method is not deterministic, and the event might be expired.
Genlocked: (IMAQ PCI/PXI 1408, IMAQ PCI/PXI 1409)
Use this mode to connect multiple cameras to one image acquisition device using a method called Genlocking, which ensures that the cameras start sending their frames simultaneously. Genlocking is the term used for sharing the timing information from one camera or source, usually referred to as the master, with one or more additional cameras, usually referred to as slaves. The image acquisition device can lock on to the timing signal of the master camera, and then digitize any of the slave camera signals using the same timing information. This method removes the delay caused by the board reacquiring and resynchronizing when another camera signal is acquired. Sharing the timing information between multiple cameras insures that when the multiplexer switches camera signals to the ADC, which occurs at the beginning of a new frame, the next camera will start sending the new frame. Therefore, there is no time delay associated with the wait for the next frame. Not all cameras have the ability to be Genlocked, and custom cabling is required. Since the cameras are Genlocked, but there is only one ADC, the highest frame rate for each channel is the Full Frame Rate of the Video Signal divided by the number of Video Signals. For example, 30 fps max / 3 cameras = 10 fps / camera. This mode can be combined with Asynchronous Reset mode for more precise timing.
Each Camera on a Separate Image Acquisition Device: (IMAQ PCI/PXI 1407, IMAQ PCI/PXI 1408, IMAQ PCI/PXI 1409, IMAQ PCI/PXI 1411)
Use this mode to connect multiple cameras to multiple image acquisition devices without asynchronous triggering. Connecting each camera signal to its own image acquisition device will insure a dedicated ADC, allowing each frame to be acquired at its full frame rate. Since there is only one camera signal for each ADC, resynchronization of the video signal is not required. The maximum delay between the trigger and acquiring a frame is a maximum of one frame period delay (30 fps has a maximum of 33.3 ms delay), because the image acquisition device waits for the next full frame. If one frame period delay is too long of a delay, then the event might be expired. This mode can be combined with Asynchronous Reset mode for more precise timing.