X20 system modules • X20 hub system • X20ET8819
X20 system User's Manual 3.10
1893
4.24.2.14 Analysis mode
Each time an incoming packet is analyzed, (see hardware configurations 1 to 3), the analysis tool saves the re-
ception timestamp, various flags and the first 'n' bytes of data from the received packet in capture frames. These
frames are sent via IF 1 (P1).
The number of recorded data bytes, 'n', is set with the operating mode switch MODE. This defines the number of
packets that are sent for each capture frame.
MODE
n
p/s
Description
0
-
-
Service mode
1
24
148800
45 packets fit in a capture frame: (1514-64) / (24+8) = 45 packets
45 packets every 300 µs
122 µs
Network being analyzed (worst case = 64 bytes / packet, packet interval of 6.7 µs)
Capture frame from the Ethernet analysis tool to the PC
2
40
148800
30 packets every 200 µs
122 µs
Capture frame from the Ethernet analysis tool to the PC
3
64
148800
This is the first setting at which complete packets fit in the capture frame (minimum packet with 60 byte payload).
20 packets can fit in one capture frame, however this setting could cause problems on the analysis PC because
there is not much idle time between the capture frames.
20 packets every 133 µs
122 µs
4
80
128000
5
120
88000
6
196
56000
7
280
40000
8
716
16000
2 packets fit in a capture frame: (716+8)*2 + 64 = 1512 bytes
A setting 'n' > 716 has the disadvantage that a network with full capacity would not be able to be analyzed.
9
24 to 1440
-
The analysis tool selects the largest possible value for 'n' itself due to the packet volume of the last capture frame
that was sent. This means that each capture frame can be assigned a different 'n' value. 'n' is always a multiple
of 4 and can assume values between 24 and 1440.
A
-
-
Up to a size of 1440 bytes every packet is recorded in its original size.
B - F
-
-
Reserved
Table 673: Analysis mode
Note:
•
A change in the position of the MODE switch from 1 to A will be applied online during operation.
•
If the S/E LED is red, then the number of bytes to be recorded should be reduced.
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