315-4PN33

The following connection-oriented protocols are supported with FBs
for open communication via Industrial Ethernet:
n TCP/IP native according to RFC 793 (connection types 01h and
11h):
–
During data transmission, no information about the length or
about the start and end of a message is transmitted.
– 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 recom-
mended 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. 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 ISO on TCP according to RFC 1006:
– During data transmission, information on the length and the
end of the message is also transmitted.
– The transfer is block-oriented
– 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.
– 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 fol-
lowing error information: ERROR = 1, STATUS = 8088h.
n There is thus no establishment and termination of a connection
with a remote partner.
n Connection-less protocols transmit data with no acknowledge and
with no reliable guaranteed delivery to the remote partner.
Connection-less pro-
tocol
VIPA System 300S Deployment Ethernet communication - productive
Configure Open Communication
HB140 | CPU | 315-4PN33 | GB | 14-43 123