Basler scout GigE, User Manual

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AW00011916000 Basler Network Drivers and Parameters
Basler scout GigE 49
Resend Request Threshold - This parameter determines the location of the resend request
threshold within the receive window as shown in Figure 28. The parameter value is in per cent of
the width of the receive window. In Figure 28 the resend request threshold is set at 33.33% of the
width of the receive window.
A stream of packets advances packet by packet beyond the resend request threshold (i.e. to the
left of the resend request threshold in Figure 28). As soon as the position where a packet is missing
advances beyond the resend request threshold, a resend request is sent for the missing packet.
In the example shown in Figure 28, packets 987 to 1005 are within the receive window and packets
997 to 999 and 1002 were detected as missing. In the situation shown, a resend request is sent to
the camera for each of the missing consecutive packets 997 to 999. The resend requests are sent
after packet 996 - the last packet of the intact sequence of packets - has advanced beyond the
resend request threshold and before packet 1000 - the next packet in the stream of packets - can
advance beyond the resend request threshold. Similarly, a resend request will be sent for missing
packet 1002 after packet 1001 has advanced beyond the resend request threshold and before
packet 1003 can advance beyond the resend request threshold.
Resend Request Batching - This parameter determines the location of the resend request
batching threshold in the receive window (Figure 28). The parameter value is in per cent of a span
that starts with the resend request threshold and ends with the front end of the receive window. The
maximum allowed parameter value is 100. In Figure 28 the resend request batching threshold is set
at 80% of the span.
The resend request batching threshold relates to consecutive missing packets, i.e., to a continuous
sequence of missing packets. Resend request batching allows grouping of consecutive missing
packets for a single resend request rather than sending a sequence of resend requests where each
resend request relates to just one missing packet.
The location of the resend request batching threshold determines the maximum number of
consecutive missing packets that can be grouped together for a single resend request. The
maximum number corresponds to the number of packets that fit into the span between the resend
request threshold and the resend request batching threshold plus one.
If the Resend Request Batching parameter is set to 0, no batching will occur and a resend request
will be sent for each single missing packet. For other settings, consider an example: Suppose the
Resend Request Batching parameter is set to 80 referring to a span between the resend request
threshold and the front end of the receive window that can hold five packets (Figure 28). In this case
4 packets (5 x 80%) will fit into the span between the resend request threshold and the resend
request batching threshold. Accordingly, the maximum number of consecutive missing packets that
can be batched is 5 (4 + 1).