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S7-400 - EXTF

3/6/2025 2:19 PM	Rate (0)
AutoGen_4091511 Member Joined: 3/15/2017 Last visit: 6/18/2025 Posts: 1 Rating: (0)	Hi all, we have a Siemens 400 series PLC with EXTF permanently lit. The batteries are fine. We have tried clearing all OB blocks. The PLC continued to run normally, but the EXTF is still lit. There is also nothing in the diagnostic buffer. HW configuration reports no error. The profinet topology is also fine. Can you advise how to proceed in finding the cause ?

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3/6/2025 2:42 PM	Rate (0)
Towome Platinum Expert Joined: 7/9/2015 Last visit: 12/17/2025 Posts: 4493 Rating: (644)	Hi, did you check manual of you PLC? There you find further informations about Status and error displays Regards, Towome
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