Remote control
R&S
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User Manual 1178.6462.02 ─ 20
6.2
Messages
The messages transferred on the data lines of the GPIB bus or via the RSIB / VXI-11
protocol can be either interface messages or device messages. For a description of
interface messages refer to the relevant sections:
●
Chapter 12.3.3, "GPIB interface"
●
Chapter 12.3.2, "LAN interface"
6.2.1
Device messages (commands and device responses)
Depending on the selected "Codec" (see
on page 1485), device messages are either transferred in ANSI, UTF-8 or Shift JIS for-
mat. 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:
● Setting commands cause instrument settings such as a reset of the instrument
or setting the output level to some value.
● Queries cause data to be provided for output on the GPIB bus, e.g. for identifi-
cation of the device or polling the active input.
2. According to their definition in standard IEEE 488.2:
● Common commands have a function and syntax that is precisely defined in
standard IEEE 488.2. Typical tasks are the management of the standardized
status registers, reset and selftest.
● Instrument-control commands are functions that depend on the features of the
instrument such as frequency settings. Most of these commands has also been
standardized by the SCPI consortium.
The device messages have a characteristic structure and syntax. In the SCPI refer-
ence chapter, all commands are listed and explained in detail.
6.2.2
SCPI command structure and syntax
SCPI commands consist of a so-called header and, usually, 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. Queries
are formed by directly appending a question mark to the header.
Common commands and device-specific commands differ in their syntax.
Messages
