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| 10/3/2012 10:26 PM | |
Joined: 9/27/2006 Last visit: 9/18/2024 Posts: 12282 Rating:
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Hello m.shoiab khatana; Siemens implements 2 types of redundancy at the processor level: software redundancy and fault-tolerant systems. In the following discussion you will find links to descriptions and analyses of both: difference between software redundancy & hardware redundancy Software redundancy can use any type and mixture of S7-300 and s7-400 standard CPUs; the redundant link between the CPUs can be implemented in standard communication links overMPI, Profibus-DP or Industrial Ethernet, and the switchover time (when a fault on the primary CPUwill cause the standby CPU to take over the process) is measured in seconds. In general terms, this can be described as a warm-backup system: relatively cheap, most of the programming for the redundancy must be done by yourself, and redundant IOs are limited. SIMATIC S7-300/S7-400 Software redundancy for SIMATIC S7 Fault-tolerant systems (built on the S7-400H CPUs) on the other hand are considered hot-backup systems. They have a dedicated fiber-optic link between the H-CPUs to update the data and program between the primary and standby CPUs constantly, and switchover is measured in milliseconds. There are integrated functions to deal with redundant IOs, and to re-integrate them when they have tripped (de-passivation blocks). Remote IOs can be addressed in redundant ET 200M stations, on through a Y-Link that connects redundant DP-masters to single-interface drives, instruments, analysers, etc... SIMATIC Fault-tolerant systems S7-400H Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 10/4/2012 1:38 AM |
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