Siemens S7-1500 PROFIBUS Operating Instructions Manual page 37

Supported program blocks for OUC
The following instructions in the specified minimum version are available for programming
Open User Communication to use FDL:
• TSEND_C V3.1 / TRCV_C V3.1
Compact blocks for connection establishment and for sending and receiving data via a
configured or programmed connection
As an alternative:
• TCON V4.0 / TDISCON V2.1
Connection establishment / connection termination
• TSEND V4.0 / TRCV V4.0
Sending or receiving data over a configured connection
• TUSEND V4.0 / TURCV V4.0
Sending or receiving data over a configured connection
With these blocks the connection parameters can be changed at runtime.
The program block can be found in STEP 7 in the "Instructions > Communication > Open User
Communication" window.
Connection description of the type "TCON_FDL"
To reference the connection description, the blocks "TCON" and "TSEND_C / TRCV_C" use the
CONNECT patrameter. The connection description is stored in a data block whose structure is
specified by the system data type (SDT) "TCON_FDL".
Creating an SDT for the data block
You create the SDT required for every connection description as a data block. You generate
the SDT type in STEP 7 by entering the name ("TCON_FDL") in the "Data type" box manually in
the declaration table of block instead of selecting an entry from the "Data type" drop-down
list. The SDT is then created with its preset parameters.
For FDL the following SDTs are used:
• TCON_FDL
For transferring data via FDL
You will find the description of TCON_FDL in the STEP 7 information system (keyword
"TCON_FDL").
Programmed connection establishment or termination with TCON / TDISCON
Connections are established using the program block TCON. Note that a separate program
block TCON must be called for each connection.
A separate connection must be established for each communications partner even if identical
blocks of data are being sent.
After a successful transfer of the data, a connection can be terminated. A connection is also
terminated by calling "TDISCON".
SIMATIC CM 1542-5
Operating Instructions, 01/2023, C79000-G8976-C290-07
Configuration, program blocks
3.6 Program blocks for FDL
37