Teledyne LeCroy USB Chief - Users Manual - Manual (Page 36)

28
Chief User’s Manual CATC Version 1.7
• Event Trigger: Recording continues in a circular manner within the limits set
by the buffer size until an event is detected on the USB bus that meets the
Trigger conditions specified in the Triggering Options and a defined amount
of data has been recorded after the Trigger Event.
Recording begins when you click on the Tool Bar.
Options
• Truncate Data Fields to 8 bytes: All data fields are truncated after the first
eight bytes.
Use this feature if you’re more concerned with recording many packets than
with collecting more data. This operation is performed by hardware to avoid
using up the Analyzer’s physical memory with non-essential data.
• Beep When Trigger Occurs: The computer connected to the USB Chief
beeps when a Trigger condition is first detected.
• Save External Interface Signals: You can save signals captured from an
external device connected to the External Interface Breakout Board.
• Reserve Memory for Traffic Generation: Half the recording memory must
be set aside for traffic generation patterns.
• Don’t automatically display recorded file: Prevents USB Chief from
automatically displaying a recorded file.
Buffer Size
You can adjust the size of the recording buffer from 0.1 megabytes to 128
megabytes.
The Recording type option determines how this buffer is used. Although there are
128 megabytes of physical memory in the Analyzer, the efficiency of the
recording ranges from 2:1 to 4:1 ratios of physical memory to actual USB traffic.
Shorter USB packets yield a less efficient recording. The non-traffic portion of
physical memory is utilized for control and timing information.
Note The scale is not linear and affords more granularity in the smaller buffer sizes.
Trigger Position
You can adjust the amount of recording to be done post-Trigger or select where
you want the Trigger located within the defined buffer. You can adjust the
Triggering Position between 1and 99% post-Trigger. Trigger Position is
available only when Manual Trigger or Event Trigger is selected as Recording
type.
As an example, if the buffer size is set to 16MB, then for the following Trigger
Position settings, the amount of pre- and post-Trigger data is
• 95% post-triggering: 0.8MB pre-trigger, 15.2MB post-trigger