Specifications

ZVx Instrument Model and Command Processing
1043.0009.50 3.147 E-15
3.7.2 Command Recognition
The command recognition analyses the data received from the input unit. It proceeds in the order in
which it receives the data. Only a DCL is serviced with priority, a GET (Group Execute Trigger), e.g., is
only executed after the commands received before as well. Each recognized command is immediately
transferred to the data set but without being executed there at once.
Syntactical errors in the command are recognized here and supplied to the status reporting system. The
rest of a command line after a syntax error is analysed further if possible and serviced.
If the command recognition recognizes a delimiter or a DCL, it requests the data set 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").
3.7.3 Data Set and Instrument Hardware
Here the expression "instrument hardware" Hdenotes the part of the instrument fulfilling the actual
instrument function - signal generation, measurement etc. The controller is not included.
The data set is a detailed reproduction of the instrument hardware in the software.
IEC-bus 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, only passes them on to the hardware when
requested by the command recognition. As this is always only effected at the end of a command line,
the order of the setting commands in the command line is not relevant.
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. All alterations
of the data set are cancelled, the instrument hardware is not reset. Due to the delayed checking and
hardware setting, however, it is permissible to set impermissible instrument states within one command
line for a short period of time without this leading to an error message. 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 3.8.3.4). 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.
IEC-bus queries induce the data set management to send the desired data to the output unit.
3.7.4 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 3.8