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Entry type: Application example Entry ID: 46817803, Entry date: 05/13/2020

Sending Emails to SMTP Servers with an S7 CPU

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  • Associated product(s)
SIMATIC S7 stations also allow the use of email as the default mechanism for transmitting error conditions or warnings from industrial plants to a control center or operating staff.

Nowadays, for security reasons, most email service providers only support an encrypted connection to their SMTP servers.

The following Ethernet ports can be used to set up a secure connection (SMTP over TLS) to an email server and send an email from the user program using the "TMAIL_C" instruction.

  • Ethernet port of S7-1500 CPU (V2.5 and higher version) or S7-1200 CPU (V4.4 or higher version)
  • Ethernet port of the CP of S7-1500 or S7-1200

Fig. 1

Setting up a secure email connection requires the following steps that are described in the application example:

  • Determine and download the provider certificates
  • Allow the email account access by the CPU or CP
  • Activate the security features in the CPU or CP
  • Import the provider certificates into STEP 7 (TIA Portal)
  • Add the provider certificates to the CPU or CP
  • Connect the Ethernet port to the Internet
  • Configure the DNS server
  • Parameterize the TMail system data types in STEP 7 (TIA Portal)
  • Parameterize the "TMAIL_C" instruction
  • Set the S7 CPU's and CP's time

  Documentation (1,7 MB) 
 Registrierung notwendig  Sample project for STEP 7 V16 (726,6 KB) 

The sample project is protected. Log on with following credentials:

  • User name: admin
  • Password: Siemens.1

The FB "PN_Mail" function block (FB490) allows you to establish a non-secure connection from the following modules to an email server:

  • S7-300/400 CPUs

  • ET200S/IM151 distributed I/O systems

  • ET200PRO/IM154-8 CPUs

  • WinAC computers such as SIMATIC Microbox PCs

In the archive, you will find the documentation and sample projects for sending unsecure emails with the FB "PN_Mail".
 Registrierung notwendig  Archive (798,7 KB)

Last Changes
Documentation for STEP 7 V16 to establish a secure connection (SMTP over TSL) to an SMTP server with an S7-1500 / S7-1200.

Security information
In order to protect technical infrastructures, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art IT security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about cyber security, please visit
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