Programming (OUC)   
5.1 Program blocks for OUC 
  CP 1542SP-1, CP 1542SP-1 IRC, CP 1543SP-1 
96  Operating Instructions, 01/2017, C79000-G8976-C426-03 
Connection descriptions in system data types (SDTs) 
For the connection description, the blocks listed above use the parameter CONNECT (or 
MAIL_ADDR_PARAM with TMAIL_C). The connection description is stored in a data block 
whose structure is specified by the system data type (SDT). 
Creating an SDT for the data blocks 
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 (e.g. "TCON_Param") 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 corresponding SDT is then created with its parameters. 
Depending on the security functions supported, the three CP types support the following 
SDTs: 
SDTs for all three CP types 
The following SDTs can be used by all three CP types: 
● 
 
For transferring frames via TCP 
● 
 
For transferring frames via UDP 
● 
 
For transferring frames via ISO-on-TCP 
● 
 
For transferring e-mails addressing the e-mail server using an IPv4 address 
● 
 
For transferring e-mails addressing the e-mail server using an IPv6 address 
● 
 
For transferring e-mails addressing the e-mail server using the host name 
You will find the description of the SDTs with their parameters in the STEP 7 information 
system under the relevant name of the SDT. 
SDT for CP 1542SP-1 IRC and CP 1543SP-1 
These two CP types can use the following SDT for e-mail connections with Security function: 
● 
 
For secure transfer of e-mails addressing the e-mail server using an IPv4 address 
● 
 
For secure transfer of e-mails addressing the e-mail server using the host name