10/11/2009 6:57 PM | |
Joined: 7/2/2008 Last visit: 8/26/2024 Posts: 928 Rating:
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Hello DesignTech, I extracted this from Fault tolerant S7-400H system manual (Page 33) 3.7 The user program The rules of developing and programming the user program for the standard S7-400 system also apply to the S7-400H. In terms of user program execution, the S7-400H behaves in exactly the same manner as a standard system. The integral synchronization functions of the operating system are executed automatically in the background. You do not need to consider these functions in your user program. In redundant operation, the user programs are stored identically on both CPUs and are executed in event-synchronous mode. However, we offer you several specific blocks for optimizing your user program, e.g. in order to improve its response to the extension of cycle times due to updates. Specific blocks for S7–400H In addition to the blocks supported both in the S7-400 and S7-400H systems, the S7-400H software provides further blocks which you can use to influence the redundancy functions. You can react to redundancy errors of the S7-400H using the following organization blocks: ● OB 70, I/O redundancy errors ● OB 72, CPU redundancy errors SFC 90 "H_CTRL" can be used to influence fault-tolerant systems as follows: ● You can disable interfacing in the master CPU. ● You can disable updating in the master CPU. ● You can remove, resume or immediately start a test component of the cyclic self-test. NOTICE Required OBs Always download these error OBs to the S7-400H CPU: OB 70, OB 72, OB 80, OB 82, OB 83, OB 85, OB 86, OB 87, OB 88, OB 121 and OB 122. If you do not download these OBs, the fault tolerant system goes into STOP when an error occurs. |
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