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Communication via Ethernet CPs in S7 Stations
IP (Internet Protocol)
For internetwork data transmission, the following services are available with
suitable CPs such as the CP 443-1 TCP:
S ISO-on-TCP connection
ISO-on-TCP is intended for reliable, internetwork data transmission.
The ISO-on-TCP service corresponds to the TCP/IP standard (Transmission
Control Protocol/Internet Protocol) with the RFC 1006 extension according to
layer 4 of the ISO reference model (see /18/).
RFC 1006 extends the TCP protocol by allowing the transmission of blocks of
data ("messages") assuming that both partners support RFC 1006.
Transmission reliability is extremely high due to automatic repetition and
additional field check mechanisms. The communications partner confirms
reception of data and the sender receives a return value on the
SEND/RECEIVE interface.
S TCP connection
When using the SEND/RECEIVE interface on TCP connections, the Ethernet
CP supports the socket interface (for example, Winsock.dll) to TCP/IP found on
almost every system (PC or other system).
TCP is intended for reliable internetwork data transmission.
The TCP service complies with the TCP/IP standard (Transmission Control
Protocol/Internet Protocol; see /18/).
S UDP connection
UDP is intended for simple internetwork data transmission without confirmation.
If the connection is suitably configured, broadcast and multicast frames can
also be sent on UDP connections.
To avoid overload due to high broadcast load, the CP does not allow reception
of UDP broadcasts. As an alternative, use the multicast function over a UDP
connection. This allows you to register the CP as a node in a multicast group.
SEND/RECEIVE interface
Data transfer is triggered by the user program. The interface to the user program in
the SIMATIC S7 is formed by special SIMATIC S7 blocks of the type FC
(functions).
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SIMATIC NET NCM S7 for Industrial Ethernet
C79000-G8976-C129–06
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