User's Manual
NPort W2150A/W2250A Series  Web Console: Serial Port Settings 
8-19 
When Operation Mode is set to Pair Connection Master or Pair Connection Slave on a serial port’s 
Operation Modes page, you will be able to configure additional settings such as TCP alive check time,
Destination address and TCP port. A Pair Connection application involves one serial port communicating 
over an IP network to another serial port as if the two serial ports were connected by a serial cable. Pair 
Connection modes can be used to extend RS-232 transmission to unlimited distances.  
An NPort device server is needed at both ends of the connection. The serial port at one end must be set to 
Pair Connection Master mode, and the serial port at the other end must be set to Pair Connection Slave 
mode. It does not matter which serial port is master and which serial port is slave. 
TCP alive check time 
Default  7 min 
Options  0 to 99 min 
Description  This field specifies how long the NPort will wait for a response to “keep-alive” packets 
before closing the TCP connection. The NPort checks connection status by sending periodic 
“keep-alive” packets.  
0: The TCP connection will remain open even if there is no response to the “keep-alive” 
packets. 
1 to 99: If the remote host does not respond to the packet within the specified time, the 
NPort will force the existing TCP connection to close. 
Destination address 
Default 
Options  IP address and port (e.g., “192.168.1.1” and “4001”) 
Description  This field specifies the IP address for the NPort at the opposite end of the Pair Connection, 
and the TCP port number for communication with the serial port. The port number must 
match with that serial port’s TCP port setting.  
TCP port 
Default  4001 
Options 
Description  This field specifies the TCP port to use for communication with the attached serial device. 
The serial port at the opposite end of the Pair Connection must use this port number to 
establish the connection. 










