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6. Socket Interface Communication
CAUTION
1. Chapter 6 presents information related to using the functions provided by the Ethernet Port from a
T2N, including the instruction (request) format, important items that require attention, and sample
programs. That chapter also presents items considered necessary when using the Ethernet Port.
Make a point of understanding the content of chapter 4 thoroughly before writing programs that use
the Ethernet Port. The sample programs present basic examples of Ethernet Port usage, and should
be reviewed carefully before use in an actual system.
This chapter describes the functions and positioning of the socket interface, and the differences
between the UDP socket interface and the TCP socket interface. Next, this chapter presents notes
on using the Ethernet Port socket interface and describes the procedures for using this
functionality.
6.1 Overview
This section describes the functions and positioning of the socket interface, and the differences
between the UDP socket interface and the TCP socket interface.
1. Positioning and functionality
The socket interface is a programming interface that allows user programs to use the TCP/IP and
UDP/IP functions. Socket interface communication is a communication technique that has become
standard on engineering workstations (EWS) and other networked computer systems.
The socket interface can be used for communication between host application programs and user
programs running on the T2N.
The Ethernet Port socket interface provides eight sockets, and the communication protocol (TCP/IP
or UDP/IP) used with the remote destination can be specified for each socket. User programs on
the T2N use the SEND and RECV instructions to use the socket interface.
TCP/IP (Transmission Control Protocol/Internet Protocol)
UDP/IP (User Datagram Protocol/Internet Protocol)
Figure 6.1 shows the positioning of the socket interface.
Application program T2N user program
OS (UNIX) T2N firmware
Socket interface Socket interface
UDP/TCP UDP/TCP
IP IP
CSMA/CD CSMA/CD
Data
communication
TCP or UDP
System
calls
SEND and RECV
instructions
Figure 6.1 Positioning of the Socket Interface
EWS T2N