Siemens SIMATIC S7-400H System Manual page 229

Job lengths and parameters for the different types of connection
Table 14- 4
Message frame
TCP
ISO-on-TCP
UDP
"local_device_id" parameter for the connection description
Dev. ID
Establishing a communication connection
● Use with TCP and ISO-on-TCP
● Use with UDP
Disconnecting a communication connection
● Use with TCP and ISO-on-TCP
● Use with UDP
S7-400H
System Manual, 03/2012, A5E00267695-11
Job lengths and "local_device_id" parameter
CPU 41x-5H PN/DP
32 KB
32 KB
1472 bytes
16#5 for CPU 0
16#15 for CPU1
Both communication partners call FB 65 "TCON" to establish the connection. In the
configuration, you specify which communication partner activates the connection, and
which one 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 layer. No connection is established to the remote partner.
The local access point is used to send and receive UDP message frames.
FB 66 "TDISCON" disconnects the communication connection between the CPU and a
communication partner.
FB 66 "TDISCON" disconnects the local communication access point, i.e., the
interconnection between the user program and the communication layer of the operating
system is terminated.
14.1 Communication services
CPU 41x-5H PN/DP with CP 443-1
-
1452 bytes
-
16#0 for CPU 0
16#10 for CPU1
Communication
229