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Entry type: Product note Entry ID: 4126780, Entry date: 08/27/1996

S5-115U - PS951 Power Supply - New Revision Level 2

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  • Associated product(s)


Concerns the product with Catalog No.:                                      


6ES5 951-7LB21   951 power supply, 120/230V AC, 3A                          




_Reason for the change:_                                                    


In the case of 951-7LB21 power supplies manufactured between                

April 1995 and August 1995, rapid OFF/ON switching can lead to              

a loss of data in the CPU.                                                  


Fault description:                                                          


- The CPU requests an overall reset (STOP LED flashes).                     

- The BATT LOW LED on the power supply is lit.                              

- User programs, data, retentive flags, times and counts stored             

  on the RAM are lost.                                                      


The fault will not occur in the case of EPROM operation without             

battery backup.                                                             


Modules manufactured during the relevant period can be identi-              

fied by the test label on the side of the module.                           


Modules with revision level 1_and_test labels                               


                          Q6F4 to Q6F8                                      


are affected.                                                               


If this is the case with any of your modules, please speak to               

your SIMATIC contact at your local Siemens office.                          




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