Communication
14.1 Communication services
S7-400H
System Manual, 03/2012, A5E00267695-11
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Job lengths and parameters for the different types of connection
Table 14- 4 Job lengths and "local_device_id" parameter
Message frame
CPU 41x-5H PN/DP
CPU 41x-5H PN/DP with CP 443-1
TCP
32 KB
-
ISO-on-TCP
32 KB
1452 bytes
UDP
1472 bytes
-
"local_device_id" parameter for the connection description
Dev. ID
16#5 for CPU 0
16#15 for CPU1
16#0 for CPU 0
16#10 for CPU1
Establishing a communication connection
●
Use with TCP and ISO-on-TCP
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.
●
Use with UDP
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.
Disconnecting a communication connection
●
Use with TCP and ISO-on-TCP
FB 66 "TDISCON" disconnects the communication connection between the CPU and a
communication partner.
●
Use with UDP
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.