19
mDNS and DNS-SD Support
Multicast DNS provides DNS services even on networks without a central DNS server (or DHCP
server). This simplifies the setting up of a simple LAN using meaningful hostnames instead of a
raw IP address. With service discovery it becomes straightforward for the device to be discovered
and the services it provides.
The services provided by the instrument are http (_http._tcp) and lxi (_lxi._tcp).
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 in software packages which communicate via a
VISA resource name. For example, an instrument at IP address 192.168.1.100 would normally
have a VISA resource name of "TCPIP0::192.168.1.100::inst0::INSTR" but for this instrument the
name must be modified to read "TCPIP0::192.168.1.100::9221::SOCKET" where 9221 is the TCP
port used by this instrument for control and monitoring, see below.
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://<hostname>: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.
TCP Sockets
The instrument uses 2 sockets 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 string must be one or more complete commands. Commands may be
separated with either semicolons “;” or line feeds. No terminator is required since the TCP frame
contains complete commands though commands may be sent with a terminator if desired (it will be
ignored). Each command over TCP behaves as if it is terminated with a command terminator
(ASCII character 0AH, line feed).
LAN Error
If a LAN connection is made but an error is detected (e.g. the IP address is the same as another
device on the network) then the instrument’s LAN lamp (above the Output 2 meters) will be off until
the error is corrected. If a LAN error occurs; check and correct the configuration of the instrument;
a LAN Configuration Initialise (LCI) mechanism is provided via a recessed switch on the rear panel
( marked LAN RESET) to reset the unit to the factory default. The default setting is for the
instrument to attempt to obtain settings via DHCP if available or, if DHCP times out (30 seconds),
via Auto-IP. In the very unlikely event that an Auto-IP address cannot be found a static IP address
of 192.168.0.100 is assigned.
If no physical LAN connection is found at any time the LAN lamp will be off.
GPIB Interface
The GPIB interface 24-way connector is located on the instrument rear panel. The pin connections
are as specified in IEEE Std. 488.1-1987 and the instrument complies with IEEE Std. 488.1-1987
and IEEE Std. 488.2-1987.
