Entry type: FAQ, Entry ID: 24048478, Entry date: 11/08/2006

How can you achieve archiving cycles of less than 500ms in WinCC Tag Logging?

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The smallest archiving cycle in WinCC Tag Logging is 500ms. There is no way of reducing this archiving cycle time through settings in WinCC Tag Logging. Shorter archiving cycles can be achieved through process-controlled archiving.

There are the following options for this:

  • "AR_SEND" (SFB37)
    In an S7-400 CPU you can implement the "AR_SEND" (SFB37) block for process-controlled archiving in WinCC. With this method the archive data is collected in the controller and then transferred to WinCC as raw data. A conversion DLL on the WinCC side interprets the data sent and enters it in the WinCC archives. You must also interconnect AR_SEND block appropriately in the controller. In WinCC you only have to assign parameters, no programming is required. Information on how to use "AR_SEND" is also available in Entry ID 23629327 and Entry ID 23629424.
  • ODK for user-specific processing of raw data
    Also with this method the data is collected in the controller and transferred to WinCC as raw data. The data is processed and archived using a conversion DLL. The "AR_SEND" (SFB37) block is not available for smaller controllers (S7-300). You have to program this function yourself. The WinCC option "WinCC Open Development Kit" (ODK) provides information on how you can process the raw data received in WinCC using your own conversion DLL.