Remote Control
R&S
®
ZNB/ZNBT
647
User Manual 1173.9163.02 ─ 38
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 10.2.3, "GPIB Interface"
●
Chapter 10.2.2, "LAN Interface"
6.2.1 Device Messages (Commands and Device Responses)
Depending on the selected "Codec" (see
on page 1140), device messages are either transferred in ANSI, UTF-8 or Shift JIS
format. 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 exactly defined in stan-
dard 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. A majority 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, in most cases, one or more param-
eters. 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
