R&S NRP2, User Manual

Page: 401 / 437

Programming Measurements
R&S
®
NRP2
383 User Manual 1173.9157.02 ─ 03
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? 'Response: valid result
FETCh:RAT? 'Response: valid result
FETCh:BURst? 'Response: -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 mea-
sured value is available, the R&S NRP2 waits for such a value and then answers the
query. During this time, no other command should be sent to the R&S NRP2, since the
query has to be answered first. If a command is sent to the R&S NRP2, 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
.
Example
CONF
TRIG:SOUR BUS
INIT
FETCh? 'Response: -214, "Trigger deadlock",
*TRG
or
GET
is not possible if
FETCh?
is waiting.
C.2 Trigger state system
The accuracy of a result largely depends on how accurately the sequence of a measure-
ment can be determined. TheR&S
NRP2 manages a trigger state system to SCPI 1999.0
for each sensor to define the exact start and stop time of a measurement. This system
defines the sequence of a measurement cycle. 4 different device states are defined in
the trigger state system implemented in the R&S
NRP2.
Trigger state system