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Statistics Summary
There are two ways to view and gather statistics.The first is to use the Statistics button, which is useful
for tracking stats during a live capture session. The second is to use the Stop button, which will append
the statistics to the end of the captured file. You should always use the Stop button at the end of a session,
particularly when you intend to send the file to Tech Support. The statistics report contains the following
information.
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Figure 27. Statistics summary
BAS-SVX51L-EN
Header — This is a summary of the link activity during the capture. The average frames and bytes
per second indicate general bandwidth utilization. The average time, in milliseconds, required for the
token to complete the circuit is the Token Rotation Time (TRT). TRT will increase on a bigger, busier
link and a very large value might indicate bandwidth saturation.
Node — These are the addresses of the devices on the link.
Nfrom — This is the number of messages from the device. You can see that where there is a gap in
the sequence, from device 3 to device 31 for example, device 3 has delivered about two thousand
more messages than the other devices. These are polling messages, seeking a device in the gap.
Polling adds to the communication overhead on the link, which is why sequential device addresses
are recommended.
Nto — This is the number of messages to the device. Note that on a clean link like this one they are
pretty uniform from one device to another.
FramesFrom — This is the number of data messages being sent (excluding token passing and
®
polling). The Tracer
SC+ at address 0 is sending many more frames than any other device.
BytesFrom — This is the number of data bytes sent from the device. The Tracer
many more bytes than any other address. On this site only devices 31-71 have been installed on the
®
Tracer
SC+. Devices 1-3 and 50-59 have not been installed on the Tracer
much smaller values in this column.
Usage% — This is the percentage of times that the device used the token to pass data. Again the
®
Tracer
SC+ wins.
TokenRetry — This is a typical clean link with very few retries. If there were duplicate addresses, there
would be a very large number at the duplicate address.
TokenFail — This shows the number of times the device failed to pass the token to a polled address.
Token Min/Max/Avg — This is the time, in milliseconds, taken for the token to complete the circuit of
®
all devices on the BACnet
Trane SerialSpy Protocol Analyzer Software
MS/TP link.
®
SC+ is sending
®
SC+, and therefore have
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