Image Transmission; Calculate Frame Rate; Usb Interface Bandwidth; Devicelinkthroughputlimit - Daheng Imaging MERCURY2 USB3 Vision User Manual

8.5. Image Transmission

8.5.1. Calculate Frame Rate

1) Frame Period
You can calculate the frame period of the MERCURY2 USB3 Vision series camera by the following formula:
T
f
Among them:
T
: The camera's frame period, unit: μs.
f
Width: The current image width.
Height: The current image height.
PixelSize: The size of the pixel, in 8bit mode, the value is 1, and in 10bit/12bit mode, the value is 2.
BandWidth : The bandwidth of the USB interface, unit: Bps.
USB
DeviceLinkThroughputLimit: The limit of the device link throughput bandwidth, unit: Bps.
T : The acquisition time of the camera, unit: μs.
acq
T : The exposure time of the camera, unit: μs.
exp
2) Frame rate (Unit: fps)
It is recommended to use the frame rate calculation tool, the frame rate will be calculated
automatically after the configuration parameters are filled.

8.5.2. USB Interface Bandwidth

The theoretical bandwidth of the USB3.0 interface is 400MBps, but actually the value will decrease with
the type of the USB3.0 host controller, the version of the host controller driver, the wastage of the HUB
and the host performance. The user can refer the test result of the interface bandwidth in <TN-USB3.0
host controller bandwidth and CPU utilization> document.

8.5.3. DeviceLinkThroughputLimit

The MERCURY2 USB3 Vision camera provides bandwidth limit function, in order to control the upper limit
bandwidth of single device. When the DeviceLinkThroughputLimit is greater than the current device
acquisition bandwidth, the current device acquisition bandwidth will not change, when the
6
ImageSize×10
= Max( ,
BandWidth
USB
ImageSize = Width × Height × PixelSize + 84
© 2023 China Daheng Group, Inc. Beijing Image Vision Technology Branch
6
ImageSize×10
DeviceLinkThroughputLimit
6
10
F =
T
f
8.Features
)
, T , T
acq exp
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