Siemens SIMATIC S7-400 Manual page 114

PROFINET
6.6 Open Communication Via Industrial Ethernet
Establishing a Connection for Communication
● Use with TCP and IS-on-CP
● Use with UDP
Disconnecting
● Use with TCP and IS-on-CP
● Use with UDP
Options for Interrupting the Communication Connection
Events causing interruptions of communication:
● You program the cancellation of connections at FB 66 "TDISCON."
● The CPU goes from RUN to STOP.
● At POWER OFF / POWER ON
Reference
For detailed information on the blocks described earlier, refer to the
6-12
Both communication partners call FB 65 "TCON" to establish the connection. In your
connection configuration, you define which communication partner activates the
connection, and which communication partner responds to the request with a passive
connection. To determine the number of possible connections, refer to your CPU's
technical specifications.
The CPU automatically monitors and holds the active connection.
If the connection is broken, for example by line interruption or by the remote
communication partner, the active partner tries to reestablish the connection. You do not
have to call FB 65 "TCON" again.
FB 66 "TDISCON" disconnects the CPU from a communication partner, as does STOP
mode. To reestablish the connection to have to call FB65 "TCON" again.
Both communication partners call FB 65 "TCON" to set up their local communication
access point. This establishes a connection between the user program and operating
system's communication level No connection is established to the remote partner.
The local access point is used to send and receive UDP telegrams.
FB 66 "TDISCON" disconnects the communication connection between CPU and
communication partner.
FB 66 "TDISCON" disconnects the local communication access point, i.e., the connection
between user program and communication level of operating system is interrupted.
STEP 7 Online Help.
S7-400 Automation System, CPU Specifications
Manual, 10/2006, 6ES7498-8AA04-8BA0