Communication
11.2 PROFINET
S7-1200 Programmable controller
826 System Manual, V4.2, 09/2016, A5E02486680-AK
Transport Control Protocol (TCP) is a standard protocol described by RFC 793:
Transmission Control Protocol. The primary purpose of TCP is to provide reliable, secure
connection service between pairs of processes. This protocol has the following features:
● An efficient communications protocol since it is closely tied to the hardware
● Suitable for medium-sized to large data amounts (up to 8192 bytes)
● Provides considerably more facilities for applications, notably error recovery, flow control,
and reliability
● A connection-oriented protocol
● Can be used very flexibly with third-party systems which exclusively support TCP
● Routing-capable
● Only static data lengths are applicable.
● Messages are acknowledged.
● Applications are addressed using port numbers.
● Most of the user application protocols, such as TELNET and FTP, use TCP.
● Programming effort is required for data management due to the SEND / RECEIVE
programming interface.
International Standards Organization (ISO) on Transport Control Protocol (TCP) (RFC 1006)
(ISO on TCP) is a mechanism that enables ISO applications to be ported to the TCP/IP
network. This protocol has the following features:
● An efficient communications protocol closely tied to the hardware
● Suitable for medium-sized to large data amounts (up to 8192 bytes)
● In contrast to TCP, the messages feature an end-of-data identification and are message-
oriented.
● Routing-capable; can be used in WAN
● Dynamic data lengths are possible.
● Programming effort is required for data management due to the SEND / RECEIVE
programming interface.
Using Transport Service Access Points (TSAPs), TCP protocol allows multiple connections
to a single IP address (up to 64K connections). With RFC 1006, TSAPs uniquely identify
these communication end point connections to an IP address.
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