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S7 IO REDUNDANCY

Created by: IICS at: 10/26/2011 1:54 PM (5 Replies)

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10/26/2011 1:54 PM	Rate (0)
IICS Posts: 5 Rating: (0)	Hi! I am doing a project that haveIOs Redundancy.So i haveone (1)ET200M and one (3)ET200M.Each of their racks have one DI card, one DO card and one AI card. Now for example i am accessing the DI say I0.0 of (1)ET200M and if an error occurs in this module then (3)ET200M will be accessible if i am right, so therefore now i will be accessing I0.0 of (3)ET200. Do i need to make any OR gate to chose which input module and/or channel is active. Same case with DO and AI. How to switch between modules. Is it enough the calling of FB450 and FB451 in OB1 so that module switching is automatic between (1)ET200M and (3)ET200M. Help is expected
IICS Posts: 5 Rating: (0)
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10/26/2011 5:14 PM	Rate (2)
H-H Platinum Member Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (309)	HelloIICS, I recommend to study theS7-400H manual(chapter 10.5) anConfiguration of Redundant I/O Modules. Although the second document is used for PCS7, but you can still use it to know how to configure the redundant I/Os in hardware configuration and to know how it works. IICS Now for example i am accessing the DI say I0.0 of (1)ET200M and if an error occurs in this module then (3)ET200M will be accessible if i am right, so therefore now i will be accessing I0.0 of (3)ET200. Do i need to make any OR gate to chose which input module and/or channel is active. Each module has a unique address. So, you can't say I0.0 of module 1 and I0.0 of module 3. You don't need any OR gate to choose which module is active. IICS Is it enough the calling of FB450 and FB451 in OB1 so that module switching is automatic between (1)ET200M and (3)ET200M. You need the following blocks: ● FC 450 "RED_INIT": Initialization function ● FC 451 "RED_DEPA": Initiate depassivation ● FB 450 "RED_IN": Function block for reading redundant inputs ● FB 451 "RED_OUT": Function block for controlling redundant outputs ● FB 452 "RED_DIAG": Function block for diagnostics of redundant I/O When you use these blocks correctly in your user program, the CPU will be able to detect which module is healthy and which is not and will do the comparison for you according to the criteria you select in HW configuration. SIMATIC MANAGER Help For digital input modules: ·Discrepancy time (maximum allowed time in which the redundant input signals can differ) When there is still a discrepancy in the input values after the configured discrepancy time has expired, a fault has occurred. ·Reaction after discrepancy This defines the reaction of the H system to a discrepancy in the input values: Use last valid value: The most recent matching value is written to the process image of the module with the lower address. No module is passivated until the next signal transition but an entry is made in the diagnostics buffer. Link signals with AND: The two read values are linked with AND for each module pair and written to the process image of the module with the lower address. No module is passivated until the next signal transition but an entry is made in the diagnostics buffer. Link signals with OR: The read values are linked with OR for each module pair and written to the process image of the module with the lower address. No module is passivated until the next signal transition but an entry is made in the diagnostics buffer. The following applies in any case: if another signal transition occurs, the module in which the transition takes place is the intact module and the other module is passivated. For analog input modules: ·Tolerance window (configured as a percent of the end value of the measuring range) Two analog values are the same when they within the tolerance window. ·Discrepancy time (maximum allowed time in which the redundant input signal can be outside the tolerance window). The set discrpancy time must be a multiple of the update time of the process image and therefore also the basic conversion time of the channels. If there is an input value discrepancy after expiration of the configured discrepancy time, there is an error. ·Applied value The applied value is the value from the two analog input values that is entered into the user program. Points to note about analog output modules Only analog output modules with current outputs can be operated redundantly (0 to 20 mA, 4 to 20 mA). Redundant analog output modules output a minimum current of approximately 120 µA per module, in other words a total of approximately 240 µA if they are passivated or if the CPU changes to STOP. Taking into account the tolerance, this means that a positive value is always output. A configured substitute value of 0 mA will result in at least these output values. In redundant mode, the configuration of the current outputs in case of a CPU STOP is set automatically to "no current or voltage". For digital outputs, all you have to do is to select the redundant modules in HW configuration. Both outputs will always have the same output value and when one of them fails the other is still giving the correct value. Best regards. H-H
	Last edited by: H-H at: 10/26/2011 7:02 PM Added digital outputs paragraph
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10/27/2011 7:22 AM	Rate (0)
IICS Posts: 5 Rating: (0)	Thanks Dear H-H for such reply I followed the manual and my HW configurations are ok. But i am confused a little bit in programming point of view. The thing which made confusion is that for example i want toread I0.0 from module-A channel1 and its equivalent redundant address is I2.0 with Module-B channel1. So i want to know that which address should i need to use in my programming logic either I0.0 or I2.0 Same for Analog inputs Should i use say PIW256 from Module-A or its equivalent redundant Address say PIW512 from Module-B. Best Regards
IICS Posts: 5 Rating: (0)
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10/27/2011 10:56 AM	Rate (0)
H-H Platinum Member Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating: (309)	HelloIICS, IICS The thing which made confusion is that for example i want toread I0.0 from module-A channel1 and its equivalent redundant address is I2.0 with Module-B channel1. So i want to know that which address should i need to use in my programming logic either I0.0 or I2.0 Always use the lower address. So you will use I0.0. IICS Same for Analog inputs Should i use say PIW256 from Module-A or its equivalent redundant Address say PIW512 from Module-B. You still have to go for the lower address which is "IW256" notP IW256 . In redundant I/Os you always have to work inside process image area which means you are not allowed to access PIW256 because In this case you will be accessing the module itself regardless the correct value that might come from PIW512. In other words, the RED_IO blocks compare PIW256 with PIW512 and the correct value is stored inIW256. Best regards. H-H

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This contribution was helpful to 4 thankful Users AGuk Ahmad Magdy samfisher fernando13

10/27/2011 11:29 AM	Rate (0)
IICS Posts: 5 Rating: (0)	Thanks dear H-H your really helpful and indeed you are.
IICS Posts: 5 Rating: (0)
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This contribution was helpful to 2 thankful Users H-H Vahid_Shahbazin

6/17/2016 11:23 AM	Rate (0)
Wit_Moderator Moderator Joined: 8/21/2014 Last visit: 11/12/2024 Posts: 1024 Rating: (14)	New question published by freedom2 is split to a separate thread with the subject Redundant CPU 414-5H module. Best regards The Helping Hand
	My Forum is the place to personalize your profile, track your topics, and maintain content that interests you. Best regards Wit_Moderator
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