Moxa Technologies 6450 - Manual (Page 2)

4- www.moxa.com e-mail: [email protected]
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Secure Terminal Server/Terminal Server
The Difference Between Device Servers,
Terminal Servers, and Console Servers
4
The terms “terminal server,” “device server,” and “console server”
can be confusing. They all refer to hardware that connects to RS-232
devices and transmits serial data using TCP/IP Telnet, SSH, or a
vendor-specific protocol. In fact, these three server types represent the
evolution of user demand for information technologies.
Terminal servers were first introduced to help engineers connect
so-called "dumb terminals" to a host computer over an Ethernet
connection. With terminal servers, data transmission is text based and
is transmitted using Telnet, TCP/IP, SSH, or some other manufacturer-
defined protocol. Terminal servers are designed to enable users
to access front-end IT equipment using PPP or dial-in/dial-out,
without using a modem. Terminal servers are generally found in IT
environments such as data centers, airports, and banks.
Before the development of Ethernet technology, terminal servers were
used to provide access to data using dial-up connections. However, as
Ethernet became more common, demand for industrial applications
also grew. Most machine-to-machine communication is serial-based,
which is effective only over short distances. This makes it difficult to
manage all equipment from a central location, which is the foundation
of industrial automation. Device servers emerged as a result.
A device server is essentially a simplified terminal server. For industrial
applications, serial-to-Ethernet communication does not require
sophisticated functionality. Device server manufacturers typically
include drivers or COM mapping functions that make things easier for
engineers who are not familiar with IT concepts. With drivers installed, serial devices can be controlled over Ethernet using legacy software,
without requiring knowledge of difficult TCP/IP routing techniques
or socket programming. Engineers can continue relying on their
knowledge of COM/TTY port programming for device control.
IP Systèmes, importateur/distributeur des solutions de communication industrielle MOXA en France Tel : 0820 200 290 (15cts/min)