YASKAWA MP920 User Manual page 163

8. DST. Port (Remote Station's Port Number)
Enter the remote station's port number (0 or 256 to 65,535) for each connection. Be sure
that the DST. IP Address and DST. Port combination are not the same as those for
another connection.
1. As shown below, if the DST. IP address and DST. Port are both set to 0, the following will result:
INFO
• DST. IP Address: 000.000.000.000
• DST. Port: 0
The connection will be in unpassive open mode, and will be made to a station that has accessed that
connection number.
If more than one station accesses a connection number in unpassive open mode, the station that first
transmitted a connection request will be connected. If a connection request is transmitted from
another station while the connection is being established, the connection that was first established
will be disconnected, and the connection will be made with the next station that issued a connection
request.
2. If the IP address and the port number do not match when the remote station's IP address and port
number are set, a connection cannot be made with the TCP protocol. The TCP connection is tempo-
rarily made, but the connection will be disconnected by the 218IF.
When setting the remote station's IP address and port number, execute a bind ( ) system call for the
socket interface of the personal computer or workstation. After allocating the port number set for
the remote station's port number to the socket, execute a connect ( ) system call and make the TCP
connection.
If the IP address and the port number do not match when the UDP protocol is used, the data in the
218IF will be discarded. As with the TCP protocol, first execute the bind ( ) system call to allocate
the port number set for the remote station's port number in the socket on the personal computer or
workstation side, and then transmit the data.
9. Connect Type (Connection Type)
Select the transport-layer protocol.
• TCP: Communications are performed using TCP (Transmission Control Protocol).
• UDP: Communications are performed using UDP (User Datagram Protocol).
Both the TCP and UDP protocols are supported by the transport-layer protocol.
10. Protocol Type
For each connection, select an application-layer protocol that is supported by the remote
station.
Port Number
TERMS
The port number is used to identify the target program at the remote station. There is a one-to-one cor-
respondence between the port number and the communications program. The port number is attached
to the data header, together with the IP address and other data. The remote station is identified by the
DST. IP Address, and data is transferred to the target program. The port number at the local station
also enables each local station and remote station communications service program to be identified.
Impassive open mode
This mode enables a connection to be established with any station that has issued a connection
request.
7-17
7.5 CP-218 Transmission Definitions
7