Additional Basics on Remote Control
R&S
®
NGP800
171
User Manual 5601.5610.02 ─ 04
are device-specific, however, their syntax follows SCPI rules as permitted by the
standard.
Instrument responses
Instrument responses (response messages and service requests) are messages which
the instrument sends to the controller after a query. They can contain measurement
results, instrument settings and information on the instrument status.
GPIB Interface Messages
Interface messages are transmitted to the instrument on the data lines with the atten-
tion line (ATN) being active (LOW). They are used for communication between the con-
troller and the instrument and can only be sent by a PC which has the function of a
GPIB bus controller. GPIB interface messages can be further subdivided into:
●
Universal commands
act on all instruments connected to the GPIB bus without
previous addressing; universal commands are encoded in the range 10 through 1F
hex. They affect all instruments connected to the bus and do not require address-
ing.
●
Addressed commands
only act on instruments previously addressed as listeners;
addressed commands are encoded in the range 00 through 0F hex. They only
affect instruments addressed as listeners.
A.1.2
SCPI Command Structure
SCPI commands consist of a so-called header and, usually, one or more parameters.
The header and the parameters are separated by a whitespace. The headers can con-
sist of several mnemonics (keywords). Queries are formed by appending a question
mark directly to the header. The commands can be either device-specific or device-
independent (common commands). Common and device-specific commands differ in
their syntax.
Syntax for Common Commands
Common (= device-independent) commands consist of a header preceded by an aster-
isk (*) and possibly one or more parameters.
Table A-1: Examples of Common Commands
Command
Command Name
Description
*RST
Reset
Resets the instrument.
*ESE
Event Status Enable
Sets the bits of the event status
enable registers.
*ESR?
Event Status Query
Queries the content of the event
status register.
*IDN?
Identification Query
Queries the instrument identifica-
tion string.
Messages and Command Structure
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