Specifications

8-10
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Serial-to-Ethernet Solutions
Serial Device Servers >
Introduction to Serial Device Servers
8
Driver Modes
Socket Modes
Other Modes
NPort® Provides a Choice of Operation Modes
TCP Server Mode
When the NPort® is configured
for TCP Server Mode, each serial
port is assigned a unique IP:Port
combination on the TCP/IP network,
and the NPort® waits passively
for a host computer to establish a
connection with the attached serial
device. TCP Server mode supports
up to 4 simultaneous connections,
allowing multiple hosts to collect
data from the same serial device at
the same time.
When the NPort® is configured
for TCP Client mode, the NPort®
establishes a TCP connection between
the attached device and a specified
host computer when data is received
from the attached device. After the
data has been transferred, the NPort®
automatically closes the connection.
TCP Client mode supports up to 4
simultaneous connections, allowing
multiple hosts to collect data from the
same serial device at the same time.
TCP Client Mode
UDP Mode
RFC2217 Mode
UDP mode supports up to 4 IP groups. In UDP mode, the
attached device can exchange data simultaneously with up to
4 network destinations, and at a higher speed than when using
TCP. This mode is ideal for message display applications.
When configured for Real COM mode,
each serial port is assigned an IP:Port
combination that is mapped to a host
computer’s local COM or TTY port using
Moxa’s NPort® drivers. Legacy applications
can access the attached serial device using
the host’s local COM or TTY port, without
the need to modify serial COM software to
account for network protocols.
When the NPort® is configured for RFC2217 mode,
each serial port is assigned an IP:Port combination
that is mapped by RFC2217-compliant drivers to
a virtual COM port. The RFC2217 protocol defines
general COM port control options based on the
Telnet protocol. The NPort® supports any third
party driver that is RFC2217-compliant.
Real COM Mode
Pair Connection Mode
When configured for Pair Connection mode, two NPort® device servers can be used to transmit RS-232 signals over Ethernet, and in this
way overcome the 15-meter limitation imposed by the RS-232 standard. One NPort® connects to the PC’s COM port, and the other NPort®
connects to the serial device. The two NPort® device servers are either connected to each other with a cross-over Ethernet cable, or are each
connected to an Ethernet LAN or WAN. Both data and modem control signals can be exchanged between the PC and device over Ethernet, but
DCD signals are not supported.
Reverse Telnet ModeEthernet Modem Mode
When configured for Ethernet
Modem mode, the serial port on
the NPort® behaves as if it were
attached to a modem, except that
data is transmitted over a network
instead of over phone lines. Ethernet
Modem Mode enables network
access for legacy software that was
originally designed to transmit data
by modem.
When configured for Reverse Telnet mode, the
NPort® device server’s serial ports provide
a connection to a server, with connections
initiated by a host over Ethernet. This is similar
to TCP server mode, except that Reverse
Telnet mode also provides Telnet-style CR/LF
conversion. Reverse Telnet mode can be used
for remote console management, in which the
NPort® is used to enable network access to
the serial console ports of different equipment,
such as routers, switches, and servers.
COM3=IP : Port
Driver Mode
TCP/IP
Ethernet
RS-232
Device
1 Request a
connection
2 Proceed with
data transmission
TCP/IP
Ethernet
TCP Client
RS-232
Device
1
2
1 Request a
connection
2 Proceed with
data transmission
TCP/IP
Ethernet
TCP Server
RS-232
Device
1
2
Directly proceed with
data transmission
(no connection required)
TCP/IP
Ethernet
RS-232
Device
RS
RS
-
2
RS
-
23
R