R&S®SML / R&S®SMV03 Messages
1090.3123.12 E-6 5.5
Messages
The messages transferred via the data lines of the IEC/IEEE bus can be divided into two groups:
– interfaces messages and
– device messages
No interface messages are defined for the RS-232-C interface.
Interface Messages
Interface messages are transferred on the data lines of the IEC/IEEE bus, the ATN control line being
active. They are used for communication between the controller and the instrument and can only be
sent by a controller which has the IEC/IEEE-bus control. Interface commands can be subdivided into
- universal commands and
- addressed commands
Universal commands act on all devices connected to the IEC/IEEE bus without previous addressing,
addressed commands only act on devices previously addressed as listeners. The interface messages
relevant to the instrument are listed in the section "Interface Messages" below.
Some control characters are defined for the control of the RS-232-C interface, see section "Interface
Functions".
Device Messages (Commands and Device Responses)
Device messages are transferred on the data lines of the IEC/IEEE bus, the ATN control line not being
active. ASCII code is used. The device messages are largely identical for the two interfaces (IEC/IEEE
bus and RS-232-C).
A distinction is made according to the direction in which device messages are sent on the IEC/IEEE bus:
– Commands are messages the controller sends to the instrument.
They operate the device functions and request information.
Commands are subdivided according to two criteria:
1. According to the effect they have on the instrument:
Setting commands cause instrument settings such as reset of the
instrument or setting the output level to 1 V.
Queries cause data to be provided for output (queries) on the
IEC/IEEE bus, eg for device identification or polling of
the active input.
2. According to their definition in standard IEEE 488.2:
Common Commands are exactly defined as to their function and notation in
standard IEEE 488.2. They refer to functions such as
the management of the standardized status registers,
reset and selftest.
Device-specific refer to functions depending on the features of the
commands instrument such as frequency setting. A majority of
these commands has also been standardized by the
SCPI committee.
– Device responses are messages the instruments sends to the controller in reply to a query. They
may contain measurement results or information on the instrument status.
The structure and syntax of device messages are described in the following section.
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