Siemens SIMATIC ET 200AL - Page 795

Open User Communication
6.11 Secure Open User Communication
Communication
Function Manual, 12/2017, A5E03735815-AF
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You use the "Remote Port" setting in the data types at the block parameter
"MAIL_ADDR_PARAM" to define which process is used for the communication.
Table 6- 6 Port numbers for the SMTPS and STARTTLS processes
Process
Port
SMTPS:
465
1
STARTTLS Any (≠465)
2
1
The instruction TMAIL_C uses SMTPS only for Port 465. For all other ports STARTTLS is used.
2
According to RFC, mail servers use Ports 25 and 587 for secure connections with STARTTLS. The
use of other port numbers for SMTP is not RFC-compliant, successful communication with such a
mail server is not guaranteed.
Example: Setting up a secure connection to a mail server over IPv4
The following section describes how to set up a secure connection to an IPv4 mail server
with the TMAIL_C communication instruction.
To set up a secure connection via the IP4 address of the mail server, follow these steps:
1. Create a global data block in the project tree.
2. Define a tag of the data type TMAIL_V4_SEC in the global data block.
The example below shows the global data block "MailConnDB" in which the tag
"MailConnectionSEC" of the data type TMAIL_V4_SEC is defined.
Figure 6-26 Data type TMAIL_V4_SEC