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Diagnostic Digital Output Fail

Created by: Rodrigo N. at: 3/12/2010 3:06 PM (2 Replies)

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3/12/2010 3:06 PM	Rate (0)
Rodrigo N. Posts: 39 Rating: (0)	Hello all, I have a newbie question. If I have a problem with the digital output of a regular module in a S7-300 system, for example, when the output transistor has a problem and get short-circuited (output level high despite the CPU command), does the CPU diagnostic this fail, or do I need to use fail safe modules? Thanks, Rodrigo S. Nakano
Rodrigo N. Posts: 39 Rating: (0)
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5/7/2010 9:54 PM	Rate (0)
mralalog Regular Member Joined: 5/7/2010 Last visit: 8/6/2012 Posts: 13 Rating: (2)	High feature standard output modules can diagnose missing L+, shorted output, and output wire break. They can't always diagnose an internal failure. You could use a standard analog input module to monitor the analog output. Do a window compare in your PLC program (to allow for the accuracy error of BOTH modules) of the analog output with the analog inputto insure that your analog output is always good. You could also use a fail safe module.

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5/8/2010 3:00 PM	Rate (0)
H-H Platinum Member Joined: 7/2/2008 Last visit: 8/26/2024 Posts: 928 Rating: (308)	Hello Rodrigo N. , Rodrigo N. If I have a problem with the digital output of a regular module in a S7-300 system, for example, when the output transistor has a problem and get short-circuited (output level high despite the CPU command), does the CPU diagnostic this fail, or do I need to use fail safe modules? There's no needfor a fail safe module to diagnose an output short circuit. You can use this module 6ES7322-8BF00-0AB0which will give you all diagnostics you are looking for. For more info on diagnostic capabilities of this module, please check page 141 in S7-300 module data manual. Best regards. H-H

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