8 Network Communication
The block library can be found for download in the ‘Service/Support’ area of
www.vipa.com at ‘Downloads è VIPA Lib’ as ‘Block library Network Communication -
SW90FS0MA’ . The library is available as packed zip file. As soon as you want to use
these blocks you have to import them into your project.
Ä
Chap. 5 ‘Include VIPA library’
page 69
8.1 Open Communication
8.1.1 Connection-oriented protocols
n Connection-oriented protocols establish a (logical) connection to the communication
partner before data transmission is started. And if necessary they terminate the con-
nection after the data transfer was finished.
n Connection-oriented protocols are used for data transmission when reliable, guaran-
teed delivery is of particular importance. Also the correct order of the received
packets is ensured.
n In general, many logical connections can exist on one physical line.
n The following connection-oriented protocols are supported with FBs for open commu-
nication via industrial Ethernet:
– TCP/IP native according to RFC 793 (connection types 01h and 11h)
– ISO on TCP according to RFC 1006 connection type 12h)
n 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.
n 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.
n 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.
n The receive block copies as many bytes into the receive area as you have specified
as length. After this, it will set NDR to TRUE and write RCVD_LEN with the value of
LEN. With each additional call, you will thus receive another block of sent data.
n During data transmission, information on the length and the end of the message is
also transmitted. The transfer is block-oriented
n 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. After this, it will set NDR to TRUE and write RCVD_LEN with the
length of the sent data.
n If you have specified the length of the data to be received less than the length of the
sent data, the receive block will not copy any data into the receive range but instead
will supply the following error information: ERROR = 1, STATUS = 8088h.
8.1.2 Connection-less protocols
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 guar-
anteed delivery to the remote partner. The following connection-oriented protocol is sup-
ported with FBs for open communication via Industrial Ethernet:
n UDP according to RFC 768 (with connection type 13h)
Block library "Network
Communication"
TCP native
ISO on TCP
VIPA SPEED7
Network Communication
Open Communication > Connection-less protocols
HB00 | OPL_SP7 | Operation list | en | 18-30 114
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