Download PicSight-GigE user manual

PicSight-GigE user manual
Initial configuration and preparation
• Multiple cameras connected to a switch are sharing a single network segment up to the receiving
PC. If they are relaying simultaneously, the total data rate might exceed the link bandwidth.
• The receiving PC might be heavily loaded, eg. by a critical real-time image processing. In such
case the resources reserved for the image processing might be temporarily limited, which could
lead to packet losses if the incoming data rate is too high.
• The camera is connected to a gigabit Ethernet network segment, but there's a slower (100Mbit)
segment on the data path. The camera would have no way to know about that bottleneck and
the packets would get dropped when reaching that segment if the camera transmits with full
gigabit speed.
The inter-packet delay feature can be found in the feature tree in category Transport Layer Control
(Section 6.4, “Transport layer control” [p. 102]), under the Stream Channel Selector. The feature is
accessible in the “expert” feature visibility level. The GenICam name of the feature is GevSCPD.
The default value is 0.
Figure 5.12. Inter-packet delay in the feature tree
The two figures below demonstrate, how packet delay should be used if multiple cameras might
be transmitting the image data simultaneously, competing for the link to the PC.
Figure 5.13. Switch dropping packets from multiple cameras due to
bottleneck in the uplink
Figure 5.14. Bottleneck resolved using inter-packet delay
Another two figures demonstrate how packet delay helps with packet processing in case of a
heavily loaded host PC.
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