R&S ZVL
Remote Control
Command Processing
Operating Manual 1303.6580.32-05
331
The command recognition detects syntax errors in the commands and transfers them to the status
reporting system. The rest of a command line after a syntax error is still executed, if possible. After the
syntax check, the range of the numerical parameters is checked, if required.
If the command recognition detects a delimiter or a
DCL
, it also requests the data set to perform the
necessary instrument hardware settings. Subsequently it is immediately prepared to process further
commands. This means that new commands can already be serviced while the hardware is still being set
("overlapping execution").
Data Base and Instrument Hardware
The expression "instrument hardware" denotes the part of the instrument fulfilling the actual instrument
function – signal generation, measurement etc. The controller is not included. The data base manages all
the parameters and associated settings required for the instrument hardware.
Setting commands lead to an alteration in the data set. The data set management enters the new values
(e.g. frequency) into the data set, however, it only passes them on to the hardware when requested by the
command recognition. This can only occur at the end of a command line, therefore the order of the setting
commands in the command line is not relevant.
The commands 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 instrument detects
that execution is not possible, an "execution error" is signalled to the status reporting system. All
alterations of the data set are cancelled, the instrument hardware is not reset. Due to the delayed
checking and hardware setting, however, impermissible instrument states can be set for a short period of
time within one command line without this leading to an error message (example: simultaneous activation
of a frequency and a power sweep). At the end of the command line, however, a permissible instrument
state must have been reached again.
Before passing on the data to the hardware, the settling bit in the
STATus:OPERation
register is set (cf.
section
STATus:OPERation Register
). The hardware executes the settings and resets the bit again as
soon as the new state has settled. This fact can be used to synchronize command servicing.
Queries induce 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 on request. The exact structure and function are described in section
Status Reporting System.
Output Unit
The output unit collects the information requested by the controller, which it receives from the data set
management. It processes it according to the SCPI rules and makes it available in the output buffer. If the
information requested is longer, it is made available "in portions" without this being recognized by the
controller.
If the instrument is addressed as a talker without the output buffer containing data or awaiting data from
the data set management, the output unit sends the error message "Query UNTERMINATED" to the
status reporting system. No data is sent on the GPIB bus or via the Ethernet, the controller waits until it
has reached its time limit. This behavior is specified by SCPI.
