Within ± 1μs
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Reducing the interval between synchronization enables it to be carried out while time
discrepancies are still small, which helps to
minimize jitter. With regards to free-running, the timing for starting camera exposure
is aligned with the time that has been synchronized with the Grand Master. Although
this is affected by the network environment,
it is ideally possible for exposure synchronous
control to be performed within 1μs (Figure 2).
It is generally necessary to prepare separate
equipment that acts as the Grand Master–
either special equipment available on the open
market, or a PC with a Linux OS and running
the free Grand Master software.
However, one area we’re investigating is the
mounting of an IEEE1588 master function
on the XCG-CG series in a future upgrade.
Doing this would turn the camera itself into
the master and eradicate the need for preparing a separate Grand Master Clock, simplifying the mechanism for synchronization
between cameras; and between cameras and
Usage scenarios and advantages
Simplification of Post-Event Analysis: Mounting IEEE1588 onto GigE Vision cameras
enables the camera to synchronize its time settings with the Grand Master Clock, and the
time stamps attached to image packets enable
absolute time to be displayed.
One of the scenarios for use with ITS
(Intelligent Transportation Systems) is the
more accurate detection of vehicles in vio-
lation of the speed limit, without the need
for radar. The time stamps obtained from
two different points will allow decisions as
to whether vehicles are exceeding the speed
limit or not to be made, and accurate times
of images obtained from both points will sim-
plify high-precision speed analysis.
IEEE1588 time stamps will also prove effec-
tive for industrial robots and all types of inspec-
tion devices used in assembly work. Adding
absolute times to images showing inspection
processing and results will enable the items in
question to be easily identified.
Improved Image Processing System Reliabil-
ity: One of the issues with installing vision sys-
tems for industrial assembly and inspection
robots and devices is the layout of the wiring.
Cables are subject to wearing and severing
when used for long-term operations, and this
causes a drop in system operability.
The chance of this increases in line
with the number of cameras in a
system–the number of cables must
also be increased if each one is to
be synchronized. The XCG-CG
Series enables multiple cameras to
be synchronized with IEEE1588
and Scheduled Action Commands.
They also support PoE (power over
Ethernet), which means that only
one cable is required for exposure
synchronization, image output and
the power supply.
Curtailment of Tact Time: One issue for
system developers and manufacturers using
such systems that still remains is the time
between image capture and peripheral equip-
ment–not supporting IEEE1588–taking
action. As such, Sony is planning to link the
new camera series to GPO (General Purpose
Output) in the future, which will enable such
peripheral equipment to be operated based on
Doing this you can see that, for example, by
connecting the camera’s GPO to robots during
the period–from the camera capturing images
to the robot performing work picking opera-
tions–will enable the image capturing and
robot operations to be synchronized.
Another example is in bottle inspection, here
devices require multiple cameras to be synchronized and for which inspection samples are
conveyed at a predetermined speed, taking this
approach will have an extremely high affinity
with systems that use the high-precision time
synchronization capabilities of IEEE1588.
Figure 2: Adjusting the exposure timing of the camera
in free run, based on the grand master. Note, while it can
be affected by the network environment, it is possible to
drive exposure synchronization to within ±1µs.
Figure 3: Sony’s XCG-CG camera series
has been equipped with a function that
begins exposure in synchronization with this
absolute time, including functions defined as
IEEE1588 applications conforming to GigE Vision standards that are known as Scheduled