Overview; Tcp Server Mode - Moxa Technologies NPort 5200 Series User Manual

Overview

NPort 5200 Serial Device Servers network-enable traditional RS-232/422/485 devices, in which a
Serial 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 NPort 5200 Serial Device Servers network-enable
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.
NPort 5200 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, NPort 5200 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 unicast or multicast
of data to only one IP or groups of IP addresses.
Pictures in this Chapter will use NPort 5400 series as an example.

TCP Server Mode

In TCP Server mode, NPort 5200 is configured
with a unique IP:Port address on a TCP/IP
network. NPort 5200 waits passively to be
contacted by the host computer, allowing the host
computer to establish a connection with and get
data from the serial device. This operation mode
also supports up to 4 simultaneous connections, so
that multiple hosts can collect data from the same
serial device—at the same time.
As illustrated in the figure, data transmission
proceeds as follows:
1. The host requests a connection from the NPort
5200 configured for TCP Server Mode.
2. Once the connection is established, data can
be transmitted in both directions—from the
host to the NPort 5200, and from the NPort
5200 to the host.
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