CTI 2572 Technical Overview Manual
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CHAPTER 5. TCP/IP OVERVIEW
5.1 TCP/IP Components
TCP/IP consists of a hierarchy of related protocols. Upper level protocols are encapsulated in the
data structure of lower level protocols.
In a typical application using the 2572, the host computer application sends PLC commands via
either TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) services. TCP is
used if connection-oriented communications is desired; UDP is used for connectionless
communications. The TCP segment or UDP datagram is placed in an IP (Internet Protocol)
datagram which is then sent to a 2572 over the network. The receiving 2572 removes the TCP
(or UDP) packet from the IP datagram, removes the PLC command from the TCP (or UDP)
packet, and transfers the PLC command to the PLC processor. Responses from the PLC are
processed in a similar manner.
Figure 11 TCP/IP Data Encapsulation
