Annex
NRP2
358User Manual 1173.9140.02 ─ 07
A.2.2 Ethernet
For remote control via a TCP/IP-based LAN, the R&S NRP2 is fitted with a
10/100BaseT Ethernet interface. The female connector is located on the rear panel of
the R&S NRP2. Via this interface, a controller can remote-control the R&S NRP2 by
means of the power meter's SCPI commands, using the VXI11 protocol (TCP/IP instru-
ment protocol specification), version 1.0, released on July 17, 1995 by the VXIbus
Consortium.
Fig. 1-2: Ethernet connector
A.2.2.1 VXI11 protocol
The VXI11 protocol uses ONC RPC (open network computing remote procedure calls),
making it possible to call R&S NRP2 functions at the source code level as if they were
running locally on the controller. The table below shows the relationships of the rele-
vant protocol layers in the OSI reference model.
Application VXI11 Network Instrument
Presentation XDR (Data representation)
Session ONC RPC
Transport TCP
Network IP
Data Link Ethernet/802.3
Physical 10/100BASE-T
Fig. 1-3: The VXI11 protocol stack in the OSI reference model
A VXI11 remote-control connection consists of three channels (core, abort and inter-
rupt), which can be used to set up as many links as desired. The concept of links
makes it possible to connect a network instrument client in a controller with several log-
ical devices in a host computer via a single VXI11 remote-control connection. A link is
then set up to each logical device. It is also possible to set up several links to one logi-
cal device, provided that several servers are running on the network instrument host or
a network instrument client is operated by several controllers. To prevent problems
caused by several controllers simultaneously accessing one device, links can be
locked. In this case, access via other links is not possible. An exception is an abort via
the abort channel, which can be executed at any time and also aborts the execution of
commands via other links.
Remote control interfaces
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