5/12/2009 2:26 PM | |
Joined: 9/27/2006 Last visit: 10/9/2024 Posts: 12285 Rating: (2685)
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Hello Yen; The fiber-optic synchronization connections are redundant. Failure of one fiber-optic cable or a single synchronization module pair will not cause the failure of the redundancy link between the 2 H-CPUs. Loss of only one link will provoque and alarm (LEDs IMF1F and/or IMF2F will become active) without causing loss of redundancy functions. You can find more on the subject in the S7-400H manual: http://support.automation.siemens.com/WW/view/en/1186523 For example: 13.1 Synchronization modules for S7-400H Function of the synchronization modules Synchronization modules are used for the communication between two redundant S7-400H CPUs. You require two synchronization modules per CPU. Connect these in pairs using fiber--optic cables. The system supports hot--swapping of synchronization modules, and thus allows you to influence the repair reaction of the redundant system and to control the failure of the redundant connection without stopping the plant. |
5/13/2009 6:21 AM | |
Joined: 9/27/2006 Last visit: 10/9/2024 Posts: 12285 Rating: (2685)
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Hello daga, H-H; Thanks for the heads-up guys; I stand corrected. Regards, Daniel Chartier |
5/14/2009 8:44 AM | |
Joined: 3/18/2009 Last visit: 5/6/2024 Posts: 306 Rating: (94) |
Dear H-H, You have clearly pointed out the ambiguity in the manual. I am not sure about all the answers but my understanding is as follows. Yes. Since synchronization is lost, a "bumpless" switch over cannot be guranteed. Hence master should continue in Run mode. Not exactly. Fault in synchronization will be detected, when a "normal" linkup is attempted. Hence the stand by CPU will switch to "Stop". Link up and update with a single pair of redundancy link (Table 9-2, last row) My understanding with an example Let's assume this initial state,
Now if I wish to make my Rack 1 CPU as master without having to stop my process, then I am still able to do it by initiating a "Switch to CPU via only one intact redundant link" from my PG or ES (See page 105 section 9.3.1 of the manual). Now the state that I will achieve is
To achieve "redundant mode" we still require "normal" linkup and update which is only possible when both the redundancy link are available. This way the statements on page 208 of chapter 13 also remain true i.e. with one "redundancy link" redundant mode for H-system is not possible. now that (though highly improbable) would be an interesting (and scary) situation. regards. |
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5/21/2009 4:49 PM | |
Posts: 9 Rating: (0) |
Thank you all for the interesting discussion. Really appreciate it. |
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