There are often questions about our cameras with CoaXPress (CXP)
interface and what the differences are to other interfaces available
on the market. We hope this brief article helps explain. With
ever increasing sensor resolutions and speed the interface to
computer has had to evolve. CoaXPress is part of this evolution.
The table below compares CXP-12 (the latest version of CoaXPress)
to four other high speed interfaces: 10GigE (standard high speed
networking interface), External PCIe (A direct connection to the
high speed internal bus of a computer), CLHS - optical (Camera
Link High Speed on an optical fibre), USB 3.1.
• Bandwidth: Since CoaXPress was published as an official
standard in 2011, the interface has become established in the
high-end machine vision sector. With the latest version 2.0 (CXP-12),
data transfer rates of 50 Gbit/s are possible. This corresponds,
for example, to a transfer rate of 280 x 16 MPixel images/sec.
• Cable length: Lengths of 40 m and more are standard
for CoaXPress and so are long enough for most machine vision applications.
When not long enough fibre repeaters are available for longer
distances.
• Triggering and real-time capability: CoaXPress offers
very accurate triggering capabilities over the same signal wires
used for image data transfer. Both data transmission and triggering
are performed with constant delay times (latency). The trigger
jitter (variation in trigger delay times) is practically negligible.
This allows for accurate synchronization of multiple cameras and
is used for synchronization with illumination or data acquisition
systems. The interface is therefore real-time capable, making
it ideal for industrial automation applications that require high
bandwidths.
• Power supply: The camera can be powered directly
via the CoaXPress interface. A local power supply is not necessary
which simplifies installation.
• Processor load and Grabber: CoaXPress requires frame
grabbers to be plugged into the computer. The advantage of using
frame grabbers is that they remove the processing load from the
PC CPU which is required to transfer data from the camera to PC
memory. This leaves the CPU free to process the image data rather
than get caught up transferring it.
• Pre-Processing: Many frame grabbers also offer the
possibility to perform calculations directly on the grabber in
real time (laser line extraction, blob, compression, etc.) which
leads to faster results and accelerates image processing.
• Usage: Since CoaXPress was published as an official
standard in 2011, the interface has become established and is
widely used in the high-end machine vision sector. There is a
wide product range with many of our suppliers offering CoaXPress
products.
• Costs: Prices for a CoaXPress setup are somewhat
more expensive than systems that use standard interfaces available
on the PC due to the need for a frame grabber. However, if you
compare the price/Gbit/s, the cost is quite favourable.
• Plug and Play: The camera communicates directly
with the frame grabber via the GeniCam standard (standardizes
the names of camera features and so allows any software to communicate
and control any camera), so no SDK is required for the camera.
All setting parameters can be controlled by the GenICam compliant
application software via the frame grabber.
• Multi-Camera: The CoaXPress interface offers the possibility
of multi-camera control. For example several cameras can be connected
to one grabber. Either one camera with 4 channels, 2 cameras with
2 channels or 4 cameras with one channel can be operated directly
on a 4-channel frame grabber.
