Siemens SIMATIC NET S7-CPs Configuring And Installing page 167

5.7.5 Free UDP connection
Program−controlled addressing
A free UDP connection allows program−controlled addressing of the
communication partner. Communication between two nodes on Industrial Ethernet
has the following properties:
S Data transfer is bi−directional; in other words it is possible to send and receive
on the UDP connection at the same time.
S The local node is specified in the configuration. The remote node is entered in
the job header of the job buffer by the user program when it calls AG_SEND.
This allows any node on Ethernet/LAN/WAN to be reached.
S The IP address and the port of the sender can be read from the job header of
AG_RECV. For information on the job header, refer to "FCs for the
SEND/RECEIVE interface" in /10/.
SIMATIC S7 station
with Ethernet CP
User data area
Job buffer
Job header
Job header
User data
User data
Figure 5-23 Sending and receiving on an unspecified UDP connection with programmed addressing
Amounts of data
Refer to the manual supplied with the Ethernet CP /1/ for the number of UDP
connections supported by the specific Ethernet CP. The number of connections per
station can be increased by adding more CPs.
Up to 2042 bytes of user data can be transferred per job buffer. The job header
uses an additional 6 bytes.
S7-CPs for Industrial Ethernet Configuring and Commissioning
Release 07/2010
C79000−G8976−C182−10
5 Configuring Communication Connections
send
unspecified
UDP connection
receive
Ethernet
node
(unspecified)
receive
send
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