NPort 5110 Series User’s Manual Choosing the Proper Operation Mode

4-3

UDP Mode
Compared to TCP communication, UDP is faster and more efficient. In UDP mode, you can
unicast or multicast data from the serial device to one or multiple host computers, and the serial
device can also receive data from one or multiple host computers, making this mode ideal for
message display applications.
Real COM Mode
NPort 5110 comes equipped with COM drivers that work with Windows 95/98/ME/NT/2000/XP
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 5110 port to a local COM port
on the host computer. 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.
ATTENTION
The driver used for Real COM Mode is installed automatically on your computer when you
install NPort 5110 Administration Suite.
One of the major conveniences of using Real COM Mode is that Real COM Mode allows users to
continue using RS-232 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 5110 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 5110’s serial
ports.
ATTENTION
Real COM Mode allows several hosts to have access control of the same NPort 5110. The driver
that comes with your NPort 5110 controls host access to attached serial devices by checking the
host’s IP address. Refer to Accessible IP Settings in Chapter 5 for more details.
Pair Connection Mode
Pair Connection Mode employs two NPort 5110 device servers in tandem, and can be used to
remove the 15-meter distance limitation imposed by the RS-232 interface. One NPort 5110 is
connected from its RS-232 port to the COM port of a PC or other type of computer, such as
hand-held PDAs that have a serial port, and the serial device is connected to the RS-232 port of the
other NPort 5110. The two NPort 5110 are then connected to each other with a cross-over Ethernet
cable, both are connected to the same LAN, or in a more advanced setup, they communicate with
each other over a WAN (i.e., through one or more routers). Pair Connection Mode transparently
transfers both data and modem control signals (although it cannot transmit the DCD signal)
between the two NPorts.