Rohde & Schwarz SMBV100A - Preventing Overlapping Execution

Remote Control Basics
R&S
®
SMBV100A
422Operating Manual 1407.6062.32 ─ 08
As a general rule, send commands and queries in different program messages.
Example: Overlapping command with *OPC
The instrument implements INITiate[:IMMediate] as an overlapped command.
Assuming that INITiate[:IMMediate] takes longer to execute than *OPC, sending
the following command sequence results in initiating a sweep and, after some time, set-
ting the OPC bit in the ESR:
INIT; *OPC.
Sending the following commands still initiates a sweep:
INIT; *OPC; *CLS
However, since the operation is still pending when the instrument executes *CLS, forcing
it into the "Operation Complete Command Idle" State (OCIS), *OPC is effectively skipped.
The OPC bit is not set until the instrument executes another *OPC command.
Example: Overlapped command followed by non-conflicting commands
Suppose that the instrument is switched on to provide a real time test signal that requires
some calculation time. At the same time some settings for the configuration of a different
signal are made which do not interact with the generated signal (e.g. the signal may be
used later on). The signal generation and the signal configuration are independent from
each other, so none of the following overlapped commands needs to be synchronized:
SOUR:BB:3GPP:STAT ON
SOUR:BB:GSM:FORM FSK2
6.4.1 Preventing Overlapping Execution
To prevent an overlapping execution of commands, one of the commands *OPC, *OPC?
or *WAI can 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 corresponding action to occur.
Table 6-2: Synchronization using *OPC, *OPC? and *WAI
Com-
mand
Action Programming the controller
*OPC Sets the Operation Complete bit in the ESR
after all previous commands have been execu-
ted.
●
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 Com-
plete bit has been set in the ESR. This bit indi-
cates that the previous setting has been com-
pleted.
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 exe-
cuted.
Sending *WAI directly after the command
whose processing should be terminated before
other commands are executed.
Command Sequence and Synchronization