Entry type: FAQ, Entry ID: 23730697, Entry date: 01/14/2009

How do you implement chronological messaging with S7-400 CPUs and WinCC?

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This entry shows you how to implement chronological messaging with an S7-400 CPU and WinCC. Chronological messaging means that the messages are sent from the PLC to the WinCC station. When they are created in the PLC, the messages are given a time stamp and then sent to the WinCC station. WinCC does not poll the PLC, which significantly reduces the bus load. The following two basic types of message and their configuration are demonstrated in the attached PDF file:
  1. Symbol-related messages
    Symbol-related messages can only be generated by CPUs of the S7-400 series. The messages are triggered asynchronously to the program.
  2. Block-related messages
    Block-related messages can be generated by CPUs of the S7-300 and S7-400 series.
    The block-related messages are created by the STEP 7 program using the system message blocks (e.g. ALARM_8P). The message is sent as soon as the STEP 7 program calls a system message block and the conditions for sending a message are fulfilled. The messages are triggered synchronously to the program.

More information

  • Reference manual "Programmable Logic Controller S7-400 CPU Data"
    This gives you detailed information on the available message procedures of a CPU. This documentation is part of the documentation package 6ES7498-8AA03-8AA0. The manual is available for downloading in Entry ID 19538001.
  • Manual "Operation List S7-400 CPU 412, 414, 416, 417"
    This gives you detailed information on available system functions and system function blocks for creating CPU messages. This documentation is part of the documentation package 6ES7498-8AA04-8AN0. The manual is available for downloading in Entry ID 1117645.
  • STEP 7 Online Help
    Detailed information on alarm processes, alarm types and system alarm blocks is available in the STEP 7 Online Help.


  • The WinCC component "AS-OS Engineering" is installed.
    You can select this component when doing a user-defined setup of WinCC. Please use the following installation sequence:
    1. STEP 7
    2. WinCC with the "AS-OS Engineering" component

    Entry ID 22272911 includes a description of how to retro-install the "AS-OS Engineering" component.

  • The WinCC project is integrated in the STEP 7 project.
    Entry ID 11841504 contains information on how to integrate a WinCC project in STEP 7.
  • The "Alarm Logging Runtime" is enabled in the startup list in the "Computer Properties" dialog of the WinCC project.

Below we show you how to configure symbol-related and block-related messages.

WinCC_ZeitfolgeRichtigMeldenS7400 ( 586 KB )

This entry has been created with WinCC V6.0 SP4 and STEP 7 V5.3 SP2. The entry was also tested with WinCC V7.0 and STEP 7 V5.4 SP4.

GMP, Pharma, Life Science, Validation, FDA 21 CFR Part 11