315-4PN33

More about the usage of the handling blocks may be found
in the manual Operation list HB00_OPL_SP7 in chapter
"VIPA specific blocks".
In the ‘open communication’ the communication takes place via the
user program by means of handling blocks. These blocks are part of
the Siemens SIMATIC Manager. You will find these in the ‘Standard
Library’
at ‘Communication Blocks’ .
n Connection-oriented protocols:
Connection-oriented protocols establish a (logical) connection to
the communication partner before data transmission is started.
And if necessary they terminate the connection after the data
transfer was finished. Connection-oriented protocols are used for
data transmission when reliable, guaranteed delivery is of partic-
ular importance. In general, many logical connections can exist on
one physical line. The following connection-oriented protocols are
supported with FBs for open communication via Industrial
Ethernet:
– TCP native accord. to RFC 793:
During data transmission, no information about the length or
about the start and end of a message is transmitted. However,
the receiver has no means of detecting where one message
ends in the data stream and the next one begins. The transfer
is stream-oriented. For this reason, it is recommended that the
data length of the FBs is identical for the sending and
receiving station. If the number of received data does not fit to
the preset length you either will get not the whole data, or you
will get data of the following job.
– ISO on TCP accord. to RFC 1006:
During data transmission, information on the length and the
end of the message is also transmitted. If you have specified
the length of the data to be received greater than the length of
the data to be sent, the receive block will copy the received
data completely into the receive range.
n Connection-less protocol:
There is thus no establishment and termination of a connection
with a remote partner. Connection-less protocols transmit data
with no acknowledge and with no reliable guaranteed delivery to
the remote partner.
– UDP accord. to RFC 768:
In this case, when calling the sending block you have to
specify the address parameters of the receiver (IP address
and port number). During data transmission, information on
the length and the end of the message is also transmitted. In
order to be able to use the sending and receiving blocks first
you have to configure the local communications access point
at both sides. With each new call of the sending block, you re-
reference the remote partner by specifying its IP address and
its port number.
Open communication
VIPA System 300S Deployment Ethernet communication - productive
Basics - Protocols
HB140 | CPU | 315-4PN33 | GB | 14-43 111