IO Industries Inc.
6.4.2 Calculate Burst Rate – CoaXPress
The following table outlines the burst rates for the CoaXPress interface at different link speeds:
Camera Interface
Maximum Burst Data Rate (MB/s)
CoaXPress
1.25Gbps
2.5Gbps
3.125Gbps
5Gbps
6.25Gbps
Single-Link
120
238
298
477
596
Dual-Link
240
476
596
954
1192
Quad-Link
480
952
1192
1908
2384
Table 24: Maximum Burst Rates of CoaXPress Interfaces
When working with a DVR Express Core 2 CoaXPress device, the burst rates shown in Table 24 can be
used to determine whether a particular camera setup will be able to be recorded without causing a
buffer overflow. Although, considering only the information in Table 24 is unnecessarily limiting. The
bandwidth limitations inherent to the DVR Express Core 2 CoaXPress devices are more difficult to
quantify than for Camera Link and are not completely described by Table 24. As an example, the
2384MB/s burst rate for Quad-Link CXP-6 is not shown in any configuration of Table 30 which would
suggest Quad-Link CXP-6 is completely unsupported. In practice, considering the maximum
instantaneous storage rate in lieu of the burst rate allows us to include many more configurations.
Use the following calculation to determine the
Maximum Instantaneous Storage Rate
in MB/s for
each camera:
Width
×
Height
×
Maximum Possible Frame Rate
×
Recorded Bytes per Pixel
1048576
Equation 2: CoaXPress Maximum Instantaneous Storage Rate
The
Width
is the horizontal resolution in pixels of the images output by the camera. The
Height
is the
vertical resolution in pixels of the images output by the camera. The
Maximum Possible
Frame Rate
is the maximum number of images output by the camera every second at the set Width and Height.
Most camera manufacturers provide a camera calculator to easily determine the maximum frame
rate a camera will operate at for any resolution. The
Recorded Bytes Per Pixel
can be determined
using the information in Table 27.
Operating the camera at a slower free-run rate or using a frame trigger at a lower rate will not
change the above calculation.
DVR Express® Core 2 MAX – User's Manual
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