EXFO FTB-1v2 Guide De L'utilisateur page 282

Using Your Unit and Modules in an Automated Test Environment
Writing Remote Control Code
Writing Remote Control Code
Your unit offers many commands permitting complete remote control of all
the supported components. These commands adhere to the SCPI
standard.
You can find all the commands and queries supported by your unit in the
IEEE 488.2 and Specific Commands appendix. For information on
commands specific to particular instruments, refer to each instrument's
user guide.
When you write code, you must follow these rules on message reception
and transmission:
The controller must have sent a complete message to the instrument

(including the message terminator) before retrieving a response.
The controller must retrieve all the responses from previous queries

(including the response terminator) before sending a new message to
an instrument.
The controller must not try to retrieve a response from an instrument if

the corresponding query has not been previously sent to the
instrument.
You must pay special attention to queries that return an indefinite ASCII

response. To avoid any confusion, the IEEE 488.2 standard requires that
this data type be immediately followed by a response termination
character. For this reason, when working with compound queries, you
must ensure that a query sending an indefinite ASCII response is the
last query of the series.
Be careful when sending program messages containing multiple

queries that return large amounts of data. Since the controller can only
retrieve data when the instrument has finished processing the queries,
it could result in problems ranging from a saturation of the output
queue to the complete blocking of the whole system.
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FTB-1v2 and FTB-1v2 Pro