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6/28/2010 3:05 PM | |
Joined: 9/27/2006 Last visit: 9/18/2024 Posts: 12282 Rating: (2684)
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Hello kumar; The following FAQ deals with handling the MMC, and holds a sample project ond SFC84: http://support.automation.siemens.com/WW/view/en/22295462 Think of an "Unlinked DB" the same way you use the hyperlink above. The contents of the DB (the data) is not available inside the PLC program until you require it; it is made reachable through a link to the MMC (SFC83). When you require it, the data can be opened and used with SFC83, when it is no longer needed you write it back with SFC84, therefore freeing work memory.. Now, in work memory, you must make sure youhave the space needed to read-in the data from the unlinked DB when you need it (if you have a number of unlinked DBs and you read one at a time, reserve space for the data in a single DB). If you are not careful to manage the unlinked DB functions, you will have a memeory overrun problem. Hope this helps, Daniel Chartier |
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