EXFO FTB-500, User Manual, Page: 238 / 449

Using FTB Products in an Automated Test Environment
230
FTB-500
Standard Status Data Structure
The following table presents a summary of the possible operations on STB
and SRE registers.
The diagram displayed on the next page is a useful aid in understanding
the general commands and how a service request (SRQ) is generated.
Using a service request, a device notifies the controller that an event
requiring special attention occurred. The controller will then find which
device generated a SRQ (its RQS bit is set) and the causes of it.
Register Read Write Clear
STB

Use *STB?.

Use serial poll (GPIB
bus sequence that
allows retrieval of the
value without
interrupting the current
process).
Impossible to write;
the register content is
only modified when
the Event registers or
Queues are modified.
Use *CLS before
sending a query (to
clear the Event registers
and Queues and by the
same token clear the
STB register).
SRE Use *SRE?. Use *SRE with a value
equal to 0 to disable
the register or with a
value equal to 1 to
enable it.

Use *SRE with a
value equal to 0.

At startup, the
register is set to 0.