R&S OSP
Remote Control
Operating Manual 1505.3896.12 - 14
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6.2.2 Device Messages (Commands and Device Responses)
Device messages are transferred via the LAN interface (VXI-11 protocol). The ASCII
character set is used. A distinction is made according to the direction in which device
messages are transferred:
Commands
are messages the controller sends to the instrument. They operate the device
functions and request information.
Device responses
are messages the instrument sends to the controller after a query. They can contain
measurement results, instrument settings and information on the instrument status.
Commands are subdivided according to two criteria:
1. According to the effect they have on the instrument:
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Setting commands
cause instrument settings such as a reset of the instrument or setting delay times
to some value.
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Queries
cause data to be provided for output on LAN, e.g. for identification of the device or
for querying I/O channel input conditions.
2. According to their definition in standard IEEE 488.2:
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Common commands
have a function and syntax that is exactly defined in standard IEEE 488.2. Typical
tasks are the management of the standardized status registers, reset and selftest.
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Instrument-control commands
are functions that depend on the features of the instrument. A majority of these
commands has also been standardized by the SCPI consortium.
The device messages have a characteristic structure and syntax. In the Remote
Command Reference chapter all commands are listed and explained in detail.
6.2.3 SCPI Command Structure and Syntax
SCPI commands consist of a so-called header and, in most cases, one or more
parameters. The header and the parameters are separated by a "white space" (ASCII
code 0 to 9, 11 to 32 decimal, e.g. blank). The headers may consist of
several mnemonics which are separated by colons. Queries are formed by appending
a question mark to the header.
SCPI defines two command types with different syntax:
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