EXFO FTB-800 Series for FTB-1 - Manual (Page 406)

Test Functions
396 FTB-700G/800 Series
FDL - Bit-Oriented Message
Receive Messages

Link Activity indicates the activity of the following parameters during
the last second of measurement.

Idle indicates that only idle codes have been detected in the last
second.

Priority indicates that at least one valid priority message has been
detected in the last second.

C/R (Command/Response) indicates that a least one valid
command and response has been detected in the last second.

Unassigned indicates that at least one unassigned message has
been detected in the last second. Therefore, since an unassigned
message is part of a Command/Response codewords, the
Command/Response LED will also be red.

PRM indicates that at least one PRM has been detected in the last
second.

Priority: The Bit-Oriented Messages are priority messages send over
the Data-Link. These messages are mostly used for networking
operation and maintenance. A Bit-Oriented Message consists of
8 consecutive 1s followed by a byte starting and ending by zeros.
Current indicates the priority message detected in the last second. If
no priority message has been detected, “--” is displayed.
Previous indicates the last priority message detected excluding the
current message. If no priority message has been detected since the
beginning of the test, “--” is displayed.
Note: See Priority on page 392 for the list of possible priority codeword messages.