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5/15/2007 5:25 PM | |
Joined: 12/5/2005 Last visit: 9/25/2024 Posts: 239 Rating: (9)
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You havethree options: A.) You maintain the structure that you are using, and use a extended pulse to guarantee a minimum duration time in each message. B.) You change the message systems of WinCC to PLC, using the TIA functions, where the PLC will send the message to WinCC, instead of WinCC polling the message. Here you have two options: B1.) Use the message system of S7-400, where is possible set the scan interval of each message to 1000ms, 500ms or 100ms. (Note here is possible to lost messages with duration below of scan interval, therefore is necessary prolong the duration of each message in PLC). B2.) Use the FBs(ALARM_8 and variations ) to generate messages in PLC. Here is more guaranteed the messages, because these blocks will generate the messages and send to WinCC. C.) Create own message buffer and use the API of WinCC to control de messages received of PLC. Anyway, I always prefer use the option B1 to all messages of PLC, and option C to guarantee the SOE (sequence of events) to messages that has precisions in order of ms, generally 1ms, using SICAM Modules of Siemens. See these posts: /tf/WW/en/Posts/7610 /tf/WW/en/Posts/5767 |
Márcio Santos |
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