Moxa Technologies NPort Server Pro User Manual download pdf (Page 8)

rial devices from a distance, either over a LAN, or even over the

Internet.

In this section, we discuss three types of application—Host-Based

Mode, Pair-Connection Mode, and Raw-Connection Mode. Read

carefully to determine which application best suits your needs.

Host-Based Mode

Traditional serial port communication uses a COM port board that

slides into one of the slots on the back of your PC. In this case, only

the computer containing the board has direct access to the board’s s e-

rial port. With Moxa’s 1-port NPort Express serial device server,

communicating with a COM port is much more versatile, since you

are now able to access the COM port from a distance, over your com-

pany’s LAN, or even over the Internet.

Pair-Connection Mode

Connecting a serial device to a PC can certainly be accomplished by

connecting the serial device directly to one of the PC’s COM ports.

This method, however, limits the maximum distance between the PC

and serial device to approximately 15 meters.

By using two NPort Expresses in tandem, the distance can be ex-

tended to half of a kilometer. One NPort Express is connected from its

RS-232 port to the COM port of the PC, the serial device is connected

to the RS-232 port of the other NPort Express, and then the two NPort

Expresses are connected to each other by an Ethernet cable.

This mode of operation provides a certain amount of flexibility. The

data from the RS-232 port of one NPort Express can be automatically

sent to the RS-232 port of the other NPort Express, without the need

for an intermediate PC or controller. NPort Express uses its own sys-

tem software to transport data back and forth between the two devices.

Raw-Connection Mode

Raw connection mode is used for standard TCP/IP socket programs

and provides transparent communication between the network socket

program and corresponding asynchronous port.

This mode of operation allows the user to easily open the asynchro-

nous serial port and read or write raw data from an Ethernet host to

the remote serial device by using an open TCP/IP socket.

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Moxa Technologies NPort Server Pro User Manual Page 8