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Entry type: FAQ Entry ID: 16993580, Entry date: 02/07/2011

What is the difference between CPU-wide messages and project-wide messages and how do you configure symbol-related messages?

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As from STEP 7 V 5.2 you can choose between two different message concepts. When you create a new project you can define the message type in the SIMATIC Manager under "Options > Settings... > Tab: Message numbers". These settings are then valid for new projects and for all those in the future.

Difference between CPU-wide Assignment and Project-wide Assignment of Message Numbers
Project-wide Assignment of Message Numbers CPU-wide Assignment of Message Numbers
The messages can be identified project-wide by a unique number. Here, the separate S7 programs are assigned a specific range of numbers in the total range available. The messages are identified by a unique CPU-wide number whereby each CPU is assigned an unchangeable number range.
You must recompile in order for the changed number to be applied in the project when you copy programs. When you copy programs, no new message number range is assigned. You only have to recompile the project if you copy single blocks.
If you subsequently change texts and attributes in the message type, you must make these changes in the instances. Subsequently changed texts and attributes in the message type are changed automatically in the instances.
Some message texts and attributes are dependent on the HMI device and must be configured for the specific display. The assigned texts and attributes depend on the HMI device.
You can create up to 2097151 messages per program for all message types (except WR_USMSG). You can create up to8191 Alarm_S messages per program. You can create up to 32767 messages per program for all other message types (except WR_USMSG).

The "CPU-wide assignment of message numbers" message concept can be used in STEP 7 V5.2 onwards in conjunction with S7-PDIAG V 5.1 onwards, WinCC V 6.0 onwards and ProTool V6.0 + SP2 onwards.

Symbol-related messages
You can only configure the symbol-related messages (message type: SCAN) for Boolean operands (inputs, outputs and markers).

  1. Open the "Message Configuration" dialog by right-clicking the desired operand in the symbol editor and selecting "Special Object Properties > Message..." in the pop-up menu.
  2. When you open the "Message Configuration" dialog for the first time and do not change the SIMATIC Manager default settings, the prompt for setting the message number assignment is displayed. Select the setting: "Assign unique message numbers CPU-wide".
  3. Confirm with "OK" and the "Message Configuration" dialog opens. More information about configuring messages is available in the Online Help which is reached by clicking the "Help" button.
    If the dialog shown in Fig. 01 is not displayed, the settings for assigning message numbers does not match. To change the settings you first save your project with the menu command "File > Save as..." and the option "With reorganization (slow)". The select the setting "Always assign unique message numbers CPU-wide" under "Tools > Settings... > Tab: Message numbers".

Fig. 01

  1. Save the symbol editor with the floppy disk symbol and generate the system data blocks (SDB) with the menu command "Edit > Generate SDB". Error-free execution is confirmed with the message "The SDB has been successfully generated".

If the CPU is replaced by another, then the messages configured CPU-wide are reassigned to the new CPU and do not have to be configured again. More information is available in the Online Help for STEP 7 under "Differences between project-wide and CPU-wide assignment of message numbers".

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