Rohde & Schwarz R&S UPP, Руководство пользователя

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Maintenance and Instrument Interfaces
R&S
®
UPP
883 User Manual 1411.1055.32 ─ 10
nection-mode communication where the sequence of the exchanged messages is
retained and interrupted connections are detected. Furthermore, messages cannot be
lost if this protocol is used.
Connection of the R&S UPP is described in Chapter 2.10.1, "Connection to the Net-
work" , on page 45, and remote control via Ethernet is described in Chapter 6.3.2,
"Remote Control via LAN Interface" , on page 641. The architecture of a LAN remote-
control connection is described in greater detail below.
Remote control of the instrument via a network is based on these standardized proto-
cols which comply with the OSI reference model (see the figure below).
Figure 9-2: Example of LAN remote control in compliance with OSI reference model (VXI-11)
Based on TCP/UDP, the messages are exchanged between the controller and the
instrument by means of Open Network Computing (ONC) Remote Procedure Calls
(RPC). With XDR, the permitted RPC messages are known as the VXI
‑
11 standard.
Messages are exchanged between the controller and the instrument based on this
standard. The messages are identical to the SCPI commands. They can be divided
into four groups: program messages (control commands to the instrument), response
messages (values returned by the instrument), service request (spontaneous requests
by the instrument) and low-level control messages (interface messages).
A VXI
‑
11 connection between a controller and an instrument is based on three chan-
nels: core, abort and interrupt channel. The instrument is controlled mainly via the core
channel (program, response and low-level control messages). The abort channel is
used for immediate termination of the core channel, and the interrupt channel trans-
ports spontaneous service requests from the instrument. The actual connection setup
is complex. Further details can be found in the VXI-11 specification ('TCP/IP Instrument
Protocol Specification VXI-11, Revision 1.0 VMEbus Extensions for Instrumentation,
VXIbus' and 'TCP/IP-IEEE 488.2 Instrument Interface Specification VXI-11.3, Draft 0.3
VMEbus Extensions for Instrumentation, VXIbus').
Instrument Interfaces