CANoe DENoe - KEMT FEI TUKE

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The post-trigger time indicates how long data continue to be acquired and saved after
the trigger condition occurs. The measurement is terminated automatically after the
post-trigger time has elapsed. Valid post-trigger times must lie in the range of 0 to
180000 ms.
2.7.1.4 Configuration of the Logging Buffer
CANoe initially saves the data arriving in the logging branch to a ring buffer in the
PC's main memory.
Under Buffer size you can define the size of the buffer in which events are saved
intermediately during a measurement. Approximately 50 bytes of memory is taken
per message; however, this memory is only reserved as needed during the measurement.
Consequently, for very large buffer sizes Windows may swap-out portions
of the main memory to the hard drive during the measurement, and this may lead to
significantly delayed program execution.
After the trigger condition occurs the ring buffer is filled with raw data until the posttrigger
time has elapsed. The user can define whether the triggering process should
be run once or multiple times. If the option Measurement stop after n trigger
blocks is chosen, then the measurement process is stopped by the logging block
after the post-trigger time of the nth trigger has elapsed. At that time it transfers data
from the ring buffer to the actual log file. Depending on the quantity of data, this
memory transfer process may involve substantial waiting times.
Since the ring buffer is limited in size, data can be lost if the pre-trigger and/or posttrigger
times are too long. Then only the last data are recorded up to the point where
the post-trigger time elapsed, and an error message is output. If necessary the
measurement can be repeated with a data reduction filter inserted upstream.
Note: If you wish to write all data to file for a long-duration measurement you
should select the option Write full buffer to file. This option causes the
buffer contents to be written to the log file during the measurement as
soon as the prescribed (maximum) buffer size is reached. The buffer size
is of decisive importance with this option. To prevent excessive system
loading during saves to the buffer, and to prevent data losses, the buffer
should not be configured to be very large. Buffers of approx. 1000 messages
have proven effective in practice. This option is only accessible in
Entire Measurement mode or in Single Trigger mode with the trigger
type Start.
To prevent data losses, especially at high system loading, you should observe the
following points:
• Close all applications that run in background and demand system time;
• Switch all blocks in the measurement setup over to Cyclic Update or disable
them entirely.
• Utilize filters for data reduction.
• Do not execute any unnecessary user actions during the measurement, such as
moving windows.
© Vector Informatik GmbH CANoe/DENoe Manual Version 4.1.1