EXFO FTB-8500 Series for FTB-500 - Manual (Page 199)

Traffic Analyzer Tabs
Ethernet and Fibre Channel Application 185
Capture

Frame Length
Allows to select the length of the frame that will be saved in the
capture buffer.

Complete captures the entire frames.

Truncated captures only the first specified number of bytes per
frame. Use either the Bytes field to manually enter the number of
bytes per frame or click on the Truncation Calculator button for
automatic bytes per frame calculation.
Bytes allows the selection of the number of bytes that will be saved
in the capture buffer for each frame captured. Choices are from
14 to 1023 bytes. The default value is 18 bytes.
Truncation Calculator allows to define the frame length in bytes
by selecting the Header layer, IP version, encapsulation, and
additional payload length of the frame. Refer to Truncation
Calculator on page 505 for more information.