R&S NRP
Annex: Remote Control - Commands
1144.1400.12
Annex - I.7
E-2
Division of MEAS?
MEAS? can be divided into other high-level measurement commands.
MEAS?
⇔
CONF [<parameters list>]
READ? [<parameters list>]
The
CONF
command configures the measurement, whereas
READ?
starts the measurement, and
calculates and provides the result. This division offers two advantages:
1. The measurement has to be configured only once and several measurements (with several
READ?
commands) can be performed in succession. This means better performance as compared to
measurements performed with
MEAS?
, since the time for configuring the measurement is only used
once.
2. After
CONF
, settings can be adapted to user’s requirements by means of low-level commands (see
below).
Note:
If a list of parameters is indicated for the READ command, it must
correspond to the list for the preceding CONF command.
After a measurement has been completed, i.e. the data from the sensors is available, it is sometimes
interesting to evaluate this data several times without starting a new measurement each time. Since this
is not possible with the above commands, the
READ?
command can be replaced by the
INIT
and
FETCh?
commands.
READ?
⇔
INIT
FETCh? [<list of parameters>]
FETCh?
evaluates existing data if the data is valid.
FETCh?
may select another calculation function if
the measurement can be evaluated with the available measured data.
Example:
The following sequence of commands provides the difference between measured values from sensors
1 and 2 by means of
FETCh:DIFF?
, which measure in the ContAv mode as the default setting.
CONF:DIFF
INIT:ALL
FETCh:DIFF?
(OK)
FETCh:RAT?
(OK)
FETCh:BURst?
(
Å
-221, "Settings conflict")
The
FETCh:RAT
? command then delivers the ratios of the two measured values. This is possible
without a new measurement, since the required data is available. The last
FETCh
command requires a
result that was measured in the BurstAv mode. Such a measured value is not available and thus, this
command will generate a SCPI error (-221, "Settings conflict").
FETCh?
immediately delivers a measured value if a valid result is available. If no measured value is
available, the R&S NRP waits for such a value and then answers the query. During this time, no other
command should be sent to the R&S NRP, since the query has to be answered first. If a command is
sent to the R&S NRP, the SCPI error -410, "Query interrupted", is output.
However,
FETCh?
should wait only if a measurement result is expected, since command processing is
blocked if a command is not answered. If
FETCh?
is executed although no measured values are
expected, the SCPI error -214, "Trigger deadlock", is output. This may occur if the trigger source is set
to
BUS
or
HOLD
with low-level
TRIG:SOUR
and
FETCh?
immediately follows
INIT
.
