Open Tcp/Ip Communication - Siemens SIMATIC NET S7-400 Manual

6.9.2

Open TCP/IP communication

Note
Validity
The information in this section applies only to the RNA interface.
Use
To allow the user program to exchange data with other TCP/IPcompliant communications
partners, STEP 7 provides a UDT for the connection parameter assignment and four
program blocks:
● UDT 65 "TCON_PAR" with the data structure for connection parameter assignment
● FB65 "TCON" for connection establishment
● FB66 "TDISCON" for connection termination
● FB63 "TSEND" for sending data
● FB64 "TRCV" for receiving data
TCP/IP communication is connectionoriented. Data can be transmitted only when a
connection has been established to the communications partner. The CPU can use several
connections to a communications partner at the same time.
The following protocol variants are supported:
● ISO on TCP according to RFC 1006
Programming
Make the following parameter settings in the connection description (UDT 65):
● local_tsap_id: Byte 1 = 0xE0 (value mandatory for correct functionality)
● local_tsap_id: Byte 2 = rack/slot number
● remote_tsap_id: Byte 1 = 0xE0 (value mandatory for correct functionality)
● remote_tsap_id: Byte 2 = rack/slot number
Note: The TSAPs can be 2-16 bytes long. The first two bytes must be occupied as
described, you can use the other bytes to suit your task.
Note
Note that the number of dynamically established connections also depends on the number of
configured, statically established connections.
You will receive corresponding condition codes on the call interface of the FBs.
Refer to the documentation of the program blocks in the online help and in the
documentation for STEP 7. There, you will also find examples of parameter assignment!
CP 443-1 RNA
Manual, 03/2019, C79000-G8976-C299-04
Configuration and operation
6.9 Interface in the user program
49