EXFO FVA-3150 Variable Attenuator - Manual (Page 57)

Controlling Your Variable Attenuator Remotely
Variable Attenuator 51
Command Structure
An SRQ is forced when a bit is set in the STB and at the same time the
corresponding SRE bit is set. When the SRQ is generated, the RQS bit is set
to 1 and remains set until read by a serial poll. Once the RQS is read, it
returns to 0.
Command Structure
The GPIB and RS-232 commands follow the guidelines determined by the
Standard Commands for Programmable Interface (SCPI) consortium.
For example, the command syntax
OUTP[:STAT]
is used to control the FVA-3150 shutter.
In this particular example:

OUTP identifies that the command is a part of the OUTPut subset
of commands;

STAT is a keyword that defines the function of the command;

[ ] indicates that a keyword or a parameter is optional;

indicates that a space is required and

is the command parameter.
All keywords must be UPPERCASE characters separated by a colon.
A typical command would be
OUTP:STAT 1
This command instructs the Variable Attenuator to optically open the
shutter.
Note: It is recommended to retrieve the response immediately after each query.