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14.4.6 LXI Discovery Tool
This tool can be used to display the IP addresses and other associated information of all connected
devices that comply with the VXI-11 discovery protocol. It is a Windows PC application, which is
provided on the supplied CD-ROM,that can be installed and run on the controlling PC, with the unit
either connected directly to the PC network connector or via a router. Double clicking on any entry in
the list of discovered devices will open the PC's web browser and display the Home page of that
device. For a later version of the tool that supports discovery by both VXI-11 and mDNS visit
www.lxistandard.org .
There are also tools for LAN discovery included as part of the National
Instruments Measurement and Automation Explorer package and the Agilent Vee application.
14.4.7 VXI-11 Discovery Protocol
The instrument has very limited support of VXI-11 which is sufficient for the discovery protocol and
no more.
It implements a Sun RPC Port-mapper on TCP port 111 and UDP port 111 as defined in RFC1183.
The calls supported are:
NULL, GET PORT and DUMP.
On TCP port 1024 a very simple VXI-11 protocol is implemented, sufficient only for instrument
discovery. This implements the following calls:
CREATE LINK, DEVICE_WRITE, DEVICE_READ and DESTROY_LINK.
Once a link has been created anything written to the device is ignored and any attempt to read from
the device returns the same identification string as the *IDN? query.
14.4.8 VISA Resource Name
Because of the limited support for VXI-11 (Discovery Protocol only), the instrument must be referred
to by its raw socket information when used with software packages which communicate using a
VISA resource name. For example, an instrument at IP address 192.168.0.100 would normally have
a VISA resource name of "TCPIP0::192.168.0.100::inst0::INSTR" but for this instrument the name
must be modified to read "TCPIP0::192.168.0.100::9221::SOCKET" where 9221 is the TCP port
used by this instrument for control and monitoring, see below.
14.4.9 XML Identification Document URL
As required by the LXI standard, the instrument provides an XML identification document that can
be queried via a GET at “http://IPaddress:80/lxi/identification” that conforms to the LXI XSD Schema
(available at http://www.lxistandard.org/InstrumentIdentification/1.0
) and the W3C XML Schema
Standards ( http://www.w3.org/XML/Schema ). This document describes the instrument. The
hostname can be used instead of the IP address if name resolution is working.
14.4.10 TCP Sockets
The instrument uses 1 socket on TCP port 9221 for instrument control and monitoring. Text
commands are sent to this port as defined in ‘Remote Commands’ and any replies are returned via
the same port. Any command string must contain one or more complete commands. Multiple
commands may be separated with either semicolons “;” or line feeds. No final terminator is required,
since the TCP frame implies a terminator, but one may be sent if desired.
15 Status Reporting
The standard status and error reporting model described in IEEE Std. 488.2 was designed for the
GPIB interface and contains some features intended for use with the Service Request and Parallel
Poll hardware capabilities of that interface, and to accommodate its semi-duplex operation. Although
those facilities are of little use with other interfaces, this instrument makes the full set of capabilities
available to all of the interfaces. All the remote interfaces share the same set of status and error
registers.
The full set of error and status registers and the individual bits they contain is shown in the Status
Model Diagram and described in detail below, but in brief the status is maintained using three
primary registers the Input Trip Register, the Standard Event Status Register and the Execution
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