Choosing The Proper Operation Mode; Overview; Real Com Mode - Moxa Technologies NPort 5000 Series User Manual

4. Choosing the Proper Operation Mode

In this chapter, we describe the NPort device server's various operation modes. The options include an
operation mode that uses a driver installed on the host computer, and operation modes that rely on TCP/IP
socket programming concepts. After choosing the proper operation mode in this chapter, refer to Chapter 5
for detailed configuration parameter definitions.

Overview

NPort serial device servers network-enable traditional RS-232/422/485 devices. A serial device server is a
small computer equipped with a CPU, real-time OS, and TCP/IP protocols that can bi-directionally translate
data between the serial and Ethernet formats. NPort device servers that are connected to a network that
with access to the Internet can be accessed from a computer located 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 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.
An NPort serial device server 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 you can continue using your existing COM/TTY-based software, 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 data to be unicast to only one IP address, or multicast
to groups of IP addresses.

Real COM Mode

The NPort comes equipped with COM drivers that work with
Windows systems, and also TTY drivers for Linux 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.
Real COM Mode also supports up to 4 simultaneous
connections, so that multiple hosts can collect data from the
same serial device at the same time.
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