Rohde & Schwarz R&S FSP Series, Operating Manual

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Operating Manual 1164.4556.12 - 06 5.17
R&S FSP Remote Control – Basics
Structure and Syntax of the Device Messages
If the command recognition recognizes a delimiter (<PROGRAM MESSAGE SEPA-
RATOR> or <PROGRAM MESSAGE TERMINATOR>) or a DCL, it requests the
instrument data base to set the commands in the instrument hardware as well now.
Subsequently it is immediately prepared to process commands again. This means
for the command servicing that further commands can already be serviced while the
hardware is still being set ("overlapping execution").
5.6.10 Instrument Data Base and Instrument Hardware
Here the expression "instrument hardware" denotes the part of the instrument fulfill-
ing the actual instrument function - signal generation, measurement etc. The con-
troller is not included.
The instrument data base is a detailed reproduction of the instrument hardware in
the software.
GPIB setting commands lead to an alteration in the data set. The data base man-
agement enters the new values (e.g. frequency) into the data base, however, only
passes them on to the hardware when requested by the command recognition.
The data are only checked for their compatibility among each other and with the
instrument hardware immediately before they are transmitted to the instrument
hardware. If the detection is made that an execution is not possible, an "execution
error" is signalled to the status reporting system. The alteration of the data base are
cancelled, the instrument hardware is not reset.
GPIB queries induce the data base management to send the desired data to the out-
put unit.
5.6.11 Status Reporting System
The status reporting system collects information on the instrument state and makes
it available to the output unit on request. The exact structure and function are
described in section
“Overview of the Status Registers” on page 5.21 .
5.6.12 Output Unit
The output unit collects the information requested by the controller, which it receives
from the data base management. It processes it according to the SCPI rules and
makes it available in the output buffer. If the instrument is addressed as a talker
without the output buffer containing data or awaiting data from the data base man-
agement, the output unit sends error message "Query UNTERMINATED" to the sta-
tus reporting system. No data are sent on the GPIB, the controller waits until it has
reached its time limit. This behavior is specified by SCPI.
5.6.13 Command Sequence and Command Synchronization
What has been said above makes clear that all commands can potentially be carried
out overlapping.
In order to prevent an overlapping execution of commands, one of commands
*OPC, *OPC? or *WAI must be used. All three commands cause a certain action
only to be carried out after the hardware has been set and has settled. By a suitable
programming, the controller can be forced to wait for the respective action to occur.