User`s manual

NPort 5600-8-DT User’s Manual Introduction to Operation Modes
5-2
Overview
The NPort 5600-8-DT connects RS-232/422/485 devices to an Ethernet network. In a typical
application, a traditional SCADA and data collection system relies on serial devices to collect data
from various kinds of instruments. With the NPort device server, the SCADA and data collection
system can access instrument data over a standard TCP/IP network, whether the devices are used
locally or at a remote site.
Each device port on the NPort 5600-8-DT is configured independently of the other device ports,
with its own serial communication parameters and operation mode. A device port’s operation
mode determines how it interacts with the network, and different modes are available to
encompass a wide variety of applications and devices.
Real COM and RFC2217 modes allow serial-based software to access the device port as if it were
a local serial port on a PC. These modes are appropriate when your application relies on Windows
or Linux software that was originally designed for locally attached COM or TTY devices. With
these modes, you can access your devices from the network using your existing COM/TTY-based
software, without investing in additional software.
Three different socket modes are available for user-developed socket programs: TCP Server,
TCP Client, and UDP Server/Client. For TCP applications, the appropriate mode depends on
whether the connection will be hosted or initiated from the device port or from the network. 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 and would be suitable for streaming media or non-critical messaging
applications such as LED message boards.
Pair Connection Slave and Master modes are designed for serial-to-serial communication over
Ethernet, in order to overcome traditional limitations with serial transmission distance.
Reverse Telnet mode is designed for connections to servers that will host terminal sessions
through the device port. This mode is typically used for console management applications, but can
also be used to upgrade legacy servers to network operation.
Real COM Mode
Real COM mode is designed to work with NPort drivers that
are installed on a network host. COM drivers are provided for
Windows systems, and TTY drivers are provided for Linux
systems. The driver establishes a transparent connection to the
attached serial device by mapping a local serial port to the
device port’s IP:Port. Real COM mode supports up to four
simultaneous connections, so multiple hosts can collect data
from the attached device at the same time.
RS-232/422/485
Driver Mode
COM3 = IP Port
Device
TCP/IP
Ethernet
Real COM Mode
Port 7
Port 8
Port 5
Port 6
Port 3
Port 4
Port 1
Port 2