R&S FSL Instrument Model and Command Processing
1300.2519.12 5.13 E-11
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 the 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. By suitable programming, the controller can be forced to wait for the respective action to occur
(refer to Table 5–1).
Table 5–1 Synchronization using *OPC, *OPC? and *WAI
Command Action Programming the controller
*OPC Sets the Operation Complete bit in
the ESR after all previous
commands have been executed.
– Setting bit 0 in the ESE
– Setting bit 5 in the SRE
– Waiting for service request (SRQ)
*OPC? Stops command processing until 1
is returned. This is only the case
after the Operation Complete bit
has been set in the ESR. This bit
indicates that the previous setting
has been completed.
Sending *OPC? directly after the command
whose processing should be terminated before
other commands can be executed.
*WAI Stops further command processing
until all commands sent before
*WAI have been executed.
Sending *WAI directly after the command whose
processing should be terminated before other
commands are executed.
An example for command synchronization can be found in chapter 7 "Remote Control – Programming
Examples".
For a couple of commands the synchronization to the end of command execution is mandatory in order
to obtain the desired result. The affected commands require either more than one measurement in
order to accomplish the desired instrument setting (e.g. auto range functions), or they require a longer
period of time for execution. If a new command is received during execution of the corresponding
function this may either lead to either to an aborted measurement or to incorrect measurement data.
The following list includes the commands, for which a synchronization via *OPC, *OPC? or *WAI is
mandatory:
Table 5–2 Commands with mandatory synchronization (overlapping commands)
Command Purpose
INIT start measurement
INIT:CONM continue measurement
CALC:MARK:FUNC:ZOOM zoom frequency range around marker 1
CALC:STAT:SCAL:AUTO ONCE optimize level settings for signal statistic
measurement functions
[SENS:]POW:ACH:PRES:RLEV optimize level settings for adjacent channel
power measurements
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