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SIMATIC S7-400 / S7-400H / S7-400F /FH: S7 416F How Towards Modify discrepancy Duration

Hi,
I have a problem with F DI module. Channels on the module are configured in 1oo2 evaluation configuration. Discrepancy time is set to 100ms but it is exceed by one channel. My problem is that on the same module is emergency signal and with the error on the other channel i lose emergency signal for certain time even if the passivate the channel is set as a behaviour after channel faults.
When i try to increase discrepancy time this module stays in fault state. When i put old value for discrepancy time module is okay. Are there any preconditions for discrepancy time change? Something that i should do before the change?
Thanks in advance,
Jovan

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Answers(1)

F DI Module Discrepancy Time & Emergency Signal Issue

Hello Jovan,

The behavior you're observing with the F DI module, specifically the loss of the emergency signal when a discrepancy fault occurs on another channel, even with "Passivate channel" set, is likely due to how the 1oo2 evaluation interacts with the module's internal fault handling. Increasing discrepancy time causing a persistent fault state also points to potential configuration issues.

Here's a breakdown and troubleshooting steps:

  1. Preconditions for Discrepancy Time Change: Yes, there are. A change in discrepancy time requires a complete module reset and potentially a restart of the safety application. Simply changing the value might not be sufficient.
  2. Check Safety Matrix: Verify your safety matrix configuration. Ensure the emergency signal isn't directly dependent on the faulty channel's status in a way that overrides the passivate behavior.
  3. Module Reset Procedure:
    • Remove power to the module.
    • Wait for at least 30 seconds.
    • Restore power.
    • After the module is online, re-enter the new discrepancy time value.
  4. Application Restart: After the module reset, restart the safety application to ensure it recognizes the new discrepancy time.
  5. SiePortal Knowledge Base: Review Siemens Industry Support for known issues and FAQs related to F DI modules and 1oo2 configurations. Search for keywords like "F DI discrepancy," "1oo2 fault," and "emergency signal loss."

If the issue persists after these steps, please provide the module's firmware version and a more detailed description of your safety matrix configuration to Siemens Support for further investigation.

Best regards,
Siemens Self Support

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