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c
HAPTER
6:
Computer Interface Operation
Model 372 AC Resistance Bridge and Temperature Controller
6.4.3 TCP Socket
Communication
A TCP socket connection interface is provided as the communication medium for the
Ethernet interface of the Model 372. A TCP socket connection, or simply “socket con-
nection”, is a common connection protocol used by Ethernet devices. The Transmis-
sion Control Protocol (TCP) is commonly used for creating a communication channel
between one program on one computer and one program on another computer, for
example a web browser on a PC and a web server on the Internet. In the case of the
Model 372, the protocol is used to create a communication channel between one
program on one computer and the command line interface of the Model 372. TCP
uses error correction and collision avoidance schemes that make it a very reliable
form of Ethernet communication, but has drawbacks of having nondeterministic tim-
ing, and can encounter relatively large delays depending on network conditions.
These delays can be on the order of seconds. Sockets use port numbers to identify
sending and receiving endpoints on network devices. This allows for multiple sepa-
rate communication links to exist on each device.
The port number used for TCP socket
connections on the Model 372 is 7777.
A maximum of two simultaneous socket connections can be made to the Model 372. Any
attempts to open a new socket while two socket connections are already open on a
Model 372 will fail.
6.4.4 Embedded Web
Interface
The Model 372 provides a web interface via an embedded web server that runs on the
instrument. Once the Model 372 is properly connected, and the IP parameters prop-
erly configured, the web interface can be opened using a web browser. The web inter-
face should be accessible using any modern web browser, but has only been tested
with Microsoft® Internet Explorer® version 11.0.
6.4.4.1 Connecting to the Web Interface
To connect to the web interface, type “http://” followed by the IP address assigned to
the Model 372 that you are attempting to connect to. If connecting from a device on
the same local network, and a hostname is properly assigned to the Model 372 via a
naming service on the network (section 6.4.1.3), then the IP address can be replaced
by the hostname. If connecting from a device not on the same local network, but on a
network which is connected to the local network of the Model 372, and a hostname
and a domain name are properly assigned, the IP address can be replaced by the host-
name followed by the domain name, with a dot separator between them. For exam-
ple if the hostname LSCI-3720001, and the domain name yourdomain.com were
assigned via a naming service, then typing “http://LSCI-3720001.yourdomain.com”
would open the home web page of the Model 372 embedded website.
6.4.4.2 Web Pages
Each web page contains detailed help information in the form of tool-tips. You can
access these tool-tips by hovering the mouse pointer over the various help icons
located throughout the embedded website.