Shad-o-Scan User Manual, Rev04
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Shad-o-Scan 3001/4501 X-Ray Detector
Teledyne DALSA
UDP Checksum Offload (IPv4)
Disable UDP Checksum Offload (IPv4).
Flow Control
The GigE Vision standard defines an inter-packet delay that can be used to manage
flow control (i.e. the speed at which stream packet can be output to the network). This
is useful when connecting multiple detectors to the same port of the network card, or
when the network card/Ethernet switch (if used) is simply too slow to process those
packets. A careful selection of equipment will ensure that the network equipment is
fast enough to handle data transmitted to the wire-speed of 5 Gigabit per second.
Therefore, inter-packet delay is typically only used when multiple detectors are
connected to the same port of the network card, through an Ethernet switch.
It is important to consider that inter-packet delay inserts a minimum delay between
image packets to spread packet transmission over a longer period of time. This can
directly impact system latency as more time than could be necessary is put in
between those packets. The best approach for real-time imaging is to dedicate a
different network port to each detector. This way, the inter-packet delay can be
eliminated in many cases.
Some network equipment also supports the optional IEEE802.3 PAUSE mechanism.
This is a low-level handshake to ensure the receiver of the packets is not
overwhelmed by the amount of data. It can propagate a pause signal back to the
transmitter, asking to momentarily stop the data transmission (with a possible impact
on the overall system latency). Again, by combining network equipment that can
operate at wire-speed and allocating a different network interface port for each
detector in the system, we can ensure these pause requests will not be used.
