Remote Control
R&S
®
FPC
349
User Manual 1178.4130.02 ─ 07
The SRQ is the only possibility for the instrument to become active on its own. Each
controller program should set the instrument in a way that a service request is initiated
in the case of malfunction. The program should react appropriately to the service
request.
Serial poll
In a serial poll, just as with command
*STB
, the status byte of an instrument is queried.
However, the query is realized via interface messages and is thus clearly faster. The
serial-poll method has already been defined in IEEE 488.1 and used to be the only
standard possibility for different instruments to poll the status byte. The method also
works with instruments which do not adhere to SCPI or IEEE 488.2.
Serial poll is mainly used to obtain a fast overview of the state of several instruments
connected to the controller.
Query by means of commands
Each part of any status register can be read by means of queries. The individual com-
mands are listed in the description of the STATus Subsystem. The returned value is
always a number that represents the bit pattern of the queried register. This number is
evaluated by the controller program.
Queries are usually used after an SRQ in order to obtain more detailed information on
the cause of the SRQ.
Error queue query
Each error state in the instrument leads to an entry in the error queue. The entries of
the error queue are detailed plain-text error messages that can be displayed via man-
ual operation using the setup menu or queried via remote control using the command
SYSTem:ERRor?
. Each call of
SYSTem:ERRor?
provides one entry from the error
queue. If no error messages are stored there any more, the instrument responds with
0, "No error".
The error queue should be queried after every SRQ in the controller program as the
entries describe the cause of an error more precisely than the status registers. Espe-
cially in the test phase of a controller program the error queue should be queried regu-
larly since faulty commands from the controller to the instrument are recorded there as
well.
19.17.11
Reset Values of the Status Reporting System
Various commands and events initiate a reset of the status reporting system. None of
the commands, except
*RST
and
SYSTem:PRESet
, influence the functional instrument
settings. In particular,
DCL
does not change the instrument settings.
Status Reporting System
