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5/28/2013 10:39 AM | |
Posts: 50 Rating: (2) |
Could any one please explain for me what is meant by channel group specific redundancy because it is not clear in the manuals ? |
7/13/2013 3:22 PM | |
Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (308)
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Hello Ayman, The term channel group specific redundancy can be found inthe400H manual. Hellomohamedsamy, I thought it's clear in the manual but I'll try to explain it maybe in different way. Basically we have 2 techniques to achieve redundancy in IO. 1- Module specific redundacy. In this technique you configure in Simatic Manager 2 different modules as redundant pair (Module A is redundant to Module B) I'll assume that we have 2 redundant modules of 6ES7331-7KF02-0AB0. This module has 8 analog channels grouped by 2. It means we have 4 groups since each 2 channels form a single group. Case 1: If a channel fault is detected in module A, the CPU passivates (Drop) all readings (8 Channels) of Module A and will take module B as correct reading for all 8 channels. Case 2: If a module fault is detected in module A, the same procedures of case 1 will happen. 2- Channel specific redundancy. In this technique you make the same typical configuration in Simtaic Manager. This means you make module A redundant to module B. I'll assume we have the same above modules (331-7KF02) Case 1: If a channel fault is detected in Channle 7 of module A, the CPU passivates the group that contains this channel. This means the CPU will passivate only group 4 that contains channel 7 and channel 8. The CPU will consider channel 7 and 8 of module B as correct values. Case 2: if a module fault is detected in module A, the whole module (8channels) will be passivated and the CPU will depend on Module B readings as in module specific redundancy. Normally I use module specific redundancy if I have the same transmitter for the 2 channels. It's very rare to have a single channel fault if you have the same signal source. I recommend channel specific redundancy (takes more memory) if you have really split signals like having 2 transmitters for the 2 channels. I hope it's more clear now and you can read more inConfiguration of Redundant I/O Modules. Best regards. H-H
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