R&S SMJ100A, Руководство по эксплуатации

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Remote Control Basics
R&S
®
SMJ100A
471 Operating Manual 1403.7458.32 ─ 14
Example: Commands and queries in one message
The response to a query combined in a program message with commands that affect
the queried value is not predictable.
The following commands always return the specified result:
:FREQ:STAR 1GHZ;SPAN 100 :FREQ:STAR?
Result:
1000000000
(1 GHz)
Whereas the result for the following commands is not specified by SCPI:
:FREQ:STAR 1GHz;STAR?;SPAN 1000000
The result could be the value of
STARt
before the command was sent since the instru-
ment might defer executing the individual commands until a program message termi-
nator is received. The result could also be 1 GHz if the instrument executes commands
as they are received.
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,
setting 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
, forc-
ing 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 sig-
nal may be used later on). The signal generation and the signal configuration are inde-
pendent 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
Command Sequence and Synchronization