EXFO FTB-2 - Manual (Page 366)

IEEE 488.2 and Specific Command Reference
356 FTB-2 and FTB-2 Pro
IEEE 488.2 Required Commands
*STB?
Description With the *STB? query you can read the status
byte and Master Summary Status bit. See the
content of this register below.
Syntax *STB?
Parameter(s) None
Response Syntax
N.U.
RQS/
MSS
ESB MAV N.U. EAV N.U. N.U.
MSB LSB Status By te Register