Rohde & Schwarz SML01, Руководство по эксплуатации

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Instrument Model and Command Processing R&S®SML / R&S®SMV03
1090.3123.12 E-6 5.14
Command Recognition
The command recognition analyzes the data from the input unit in the order the data are received. Only
DCL commands are serviced with priority, whereas GET commands (Group Execute Trigger), for
example, are processed only after the previously received commands. Each recognized command is
immediately transferred to the data set but without being executed there at once.
Syntactic errors in commands are detected here and transferred to the status reporting system. The rest
of a command line following a syntax error is further analyzed and processed as far as possible.
If the command recognition recognizes a terminator or a DCL command, it requests the data set to set
the commands now also in the instrument hardware. After this, it is immediately ready to continue
processing commands. This means that new commands can be processed while the hardware is being
set ("overlapping execution").
Data Set and Instrument Hardware
The term "instrument hardware" is used here to designate the part of the instrument which actually
performs the instrument functions: signal generation, measurement, etc. The controller is not included.
The data set is a detailed reproduction of the instrument hardware in the software.
IEC/IEEE-bus setting commands cause an alteration of the data set. The data set management enters
the new values (eg frequency) into the data set but passes them on to the hardware only upon request
by the command recognition. As this is only effected at the end of a command line, the sequence of
setting commands in the command line is not relevant.
The data are only checked for compatibility among one another and with the instrument hardware
immediately before they are transferred to the instrument hardware. If it is found that an execution is not
possible, an "execution error" is signalled to the status reporting system. All alterations mad to the data
set are cancelled, and the instrument hardware is not reset. Due to the delayed checking and hardware
setting it is permissible however that impermissible instrument states are briefly set within a command
line without an error message being produced. At the end of the command line, however, a permissible
instrument state must be attained.
Before the data are passed on to the hardware, the settling bit in the STATus:OPERation register is set.
The hardware makes the settings and resets the bit when the new state has settled. This procedure can
be used for synchronization of command processing.
IEC/IEEE-bus queries cause the data set management to send the desired data to the output unit.
Status Reporting System
The status reporting system collects information on the instrument state and makes it available to the
output unit upon request. A detailed description of the structure and function is given in section "Status
Reporting System".