Rohde & Schwarz R&S UPP, User Manual

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Remote Control - Fundamentals
R&S
®
UPP
649 User Manual 1411.1055.32 ─ 10
the instrument and can only be sent by a controller which has controller functionality on
the IEC/IEEE bus.
Interface messages can be further classified as
●
– Universal commands
●
– Addressed commands
Universal commands affect all devices connected to the IEC/IEEE bus without requir-
ing an address, whereas addressed commands only affect devices addressed as a lis-
tener. The interface messages relevant for a device are listed in
Chapter 9.4, "Instru-
ment Interfaces" , on page 879.
If an Ethernet connection is present, signaling on a hardware control line is not
required. The IEC/IEEE bus interface commands are emulated (see
Chapter 9.4,
"Instrument Interfaces" , on page 879).
6.4.2 Device-Dependent Messages
Device-dependent messages are transmitted on the data lines of the IEC/IEEE bus
when the ATN control line is not active. ASCII code is used for data transmission.
If an Ethernet connection is present, signaling on a hardware control line is not
required.
Device-dependent messages are identical for the two interfaces (IEC/IEEE bus and
Ethernet). They are differentiated by the direction in which they are sent:
Commands (program messages)
are messages sent by the controller to a device. They operate device functions and
request information.
These commands are in turn differentiated by two criteria:
1. The effect they have on the device:
Setting commands trigger device settings, e.g. a device reset or set-
ting of the generator frequency.
Queries cause data to be put in the output queue, e.g. for
device identification or querying a setting. These
commands are formed by adding a question mark
to the setting command.
2. Their definition in the IEEE 488.2 and SCPI standard:
Messages