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Section 10: Cameras
Section 10.1: Digital Camera Interfaces
152 +44 (0) 1904 788600 | Edmund Optics® targets Digital cameras are available with a variety of interface options that
are often dependent on an application's requirements. Some formats,
such as the USB varieties, can greatly simplify the setup process with
Plug-n-Play features and by supplying video output and power via
a single cable. Other formats may require an additional power supply
or other peripherals but provide advantages such as higher data
transfer rates, which affects the camera's frame rate, or support longer
cable length and a greater number of simultaneous devices. Table 10.1
compares the different digital camera interfaces.
Table 10.1: Comparison of popular digital camera interfaces.
For more information on cameras go to
www.edmundoptics.eu/cameras
Digital Interface Comparison
DIGITAL SIGNAL
OPTIONS
NOTE: images not
drawn to scale
USB 3.1 GigE (PoE) 5 GigE (PoE) 10 GigE (PoE) CoaXPress Camera Link®
Data Transfer Rate: 5 Gb/s 1000 Mb/s 5 Gb/s 10 Gb/s up to 12,5 Gb/s up to 6,8 Gb/s
Max Cable Length: 3 m (recommended) 100 m, Cat5e or 6 100 m, Cat5e or 6 100 m, CAT6a and
above/10 km, Optical Cabling >100 m at 3,125 Gb/s 10 m
# Devices: up to 127 Unlimited Unlimited Unlimited Unlimited 1
Connector: USB 3.1 Micro B/USB-C RJ45/M12 RJ45/M12 RJ45/M12/SFP+ RG59 / RG6 / RG11 26 pin
Capture Board: Optional Not Required Not Required Not Required Optional Required
External Power: Optional Required (Optional with PoE) Required (Optional with PoE) Required (Optional with PoE) Optional Required
USB (Universal Serial Bus)
USB 3.1 Gen 1, formerly known as USB 3,0, is a popular interface
because of its ubiquity among computers, its high speed, and its convenience.
Maximum attainable speed and convenient; maximum attainable
speed depends upon the number of USB peripheral components,
as the transfer rate of the bus is fixed at 5 Gb/s. In USB3 Vision,
camera control registers are based on the EMVA GenICam standard.
The USB3 Vision standard does not match that of the computer standard
of backwards compatibility, but some USB 3.1 Gen 1 cameras
are backward compatible. However, they run at the slower speed of
USB 2.0 (480 Mb/s). The most common USB 3.1 connector used in
the machine vision camera industry is the USB 3.1 Micro B connector.
Gradually being introduced to the market is USB-C (USB Type C), the
connection type designed for the future. It features single and dual
band top speeds of 10 and 20 Gb/s respectively. Additionally, this
connector has a smaller footprint and is reversable. While cables and
cameras that currently use USB-C are still limited to USB 3.1 Gen 1
data transmission speeds, this newer connector will be required as the
industry adopts USB 3.1 Gen 2 as an alternative high-speed interface.
GigE (Gigabit Ethernet)
GigE is based on the gigabit ethernet internet protocol and uses standard
Cat 5e and Cat 6 cables for a high-speed camera interface. Standard
ethernet hardware such as switches, hubs, and repeaters can
be used for multiple cameras, although overall bandwidth must be
considered whenever non peer-to-peer (direct camera to card) connections
are used. In GigE Vision, camera control registers are based
on the EMVA GenICam standard. Optional on some cameras, Link
Aggregation (LAG) uses multiple ethernet ports in parallel to increase
data transfer rates. Also supported by some cameras, the network
Precision Time Protocol (PTP) can be used to synchronize the clocks
of multiple cameras connected on the same network, allowing for a
fixed delay relationship between their associated exposures. 5 GigE
and 10 GigE are newer versions of the GigE interface that feature data
transfer rates of 5 Gb/s and 10 Gb/s, respectively.
CoaXPress
CoaXPress is a plug-and-play high-speed digital interface for use in
high-resolution machine vision applications that require a fast frame
rate. It uses a coaxial cable and is scalable for multiple cables; each
cable is capable of up to 12,5 Gb/s, and each cable can provide up
to 13 W of power at a nominal 24 V. Because of this scalability, there
is no set maximum for a cable length with CoaXPress; the higher the
bandwidth, the smaller the maximum cable length.
Camera Link®
Camera Link® is a high-speed serial interface standard developed
explicitly for machine vision applications. A Camera Link® capture
card is required for use, and power must be supplied separately to
the camera. Special cabling is required because, in addition to lowvoltage
differential pair (LVDP) signal lines, separate asynchronous
serial communication channels are provided to retain full bandwidth
for data transmission. The single-cable base configuration allows 2,04
Gb/s transfer dedicated for video. Dual outputs (full configuration) allow
for separate camera parameter send/receive lines to free up more
data transfer space (6,8 Gb/s) in extreme high-speed applications.
Capture Boards
Image processing typically involves the use of computers, which
means a digital interface is necessary when using analog cameras.
Capture boards allow users to output analog camera signals into a
computer for analysis; for analog signals (NTSC, YC, PAL, CCIR), the
capture board contains an analog-to-digital converter (ADC) to digitize
the signal for further image processing. Users can then capture
images and save them for future manipulation and printing. Basic
capturing software is included with capture boards, allowing users to
save, open, and view images.
The term capture board also refers to cards that are necessary to acquire
and interpret the data from digital camera interfaces but are not
based on standard computer connectors.
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