User`s manual

NPort S8000 Series Choosing the Serial Operation Mode
4-2
Overview
The device server function of the NPort S8000 enables network operation of traditional RS-232/422/485
devices, in which a device server is a tiny computer equipped with a CPU, real-time OS, and TCP/IP protocols
that can bi-directionally translate data between the serial and Ethernet formats. Your computer can access,
manage, and configure remote facilities and equipment over the Internet from anywhere in the world.
Traditional SCADA and data collection systems rely on serial ports (RS-232/422/485) to collect data from
various kinds of instruments. Since the NPort S8000 networks instruments equipped with an RS-232/422/485
communication port, your SCADA and data collection system will be able to access all instruments connected
to a standard TCP/IP network, regardless of whether the devices are used locally or at a remote site.
The NPort S8000 is an external IP-based network device that allows you to expand the number of serial ports
for a host computer on demand. As long as your host computer supports the TCP/IP protocol, you won’t be
limited by the host computer’s bus limitation (such as ISA or PCI), or lack of drivers for various operating
systems.
In addition to providing socket access, the NPort also comes with a Real COM/TTY driver that transmits all serial
signals intact. This means that your existing COM/TTY-based software can be preserved, without needing to
invest in additional software.
Three different Socket Modes are available: TCP Server, TCP Client, and UDP Server/Client. The main
difference between the TCP and UDP protocols is that TCP guarantees delivery of data by requiring the recipient
to send an acknowledgement to the sender. UDP does not require this type of verification, making it possible
to offer speedier delivery. UDP also allows multicasting of data to groups of IP addresses.
Real COM Mode
The
NPort S8000 comes equipped with COM drivers that
work with Windows 9x/NT/2000/XP/2003/Vista/2008 (all
x86/x64)
systems, and also TTY drivers for Linux
and Unix
systems. The driver establishes a transparent connection
between host and serial device by mapping the IP port of
the NPort’s serial port to a local COM/TTY port on the host
computer.
This operation mode also supports up to 8
simu
ltaneous connections, so that multiple hosts can
collect data from the same serial device at the same time.
The important point is that Real COM Mode allows users to continue using RS-232/422/485 serial
communications software that was written for pure serial communications applications. The driver intercepts
data sent to the host’s COM port, packs it into a TCP/IP packet, and then redirects it through the host’s Ethernet
card. At the other end of the connection, the NPort accepts the Ethernet frame, unpacks the TCP/IP packet, and
then transparently sends it to the appropriate serial device attached to one of the NPort’s serial ports.
ATTENTION
Real COM
Mode allows several hosts to have access control over the same NPort. The driver that comes
with
your NPort controls host access to attached serial devices by checking
the host’s IP address.
Modify the
Accessible IP Setting table when the legal IP address is required in your application