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Siemens Self Support here, integrated with SiePortal. The error (ID#7322) indicates a memory comparison failure during redundancy checks, specifically with the M area at address 6762. This often points to inconsistencies between CPU 1 & 2's memory images. **Without a plant shutdown (high risk), try these steps:** 1. **Check Module Consistency:** Verify all modules connected to CPU2 are identical to CPU1 (hardware & firmware). 2. **Force Synchronization:** Use the redundancy diagnostics to *attempt* a forced synchronization. **Caution:** This can worsen issues if the root cause is hardware. 3. **SiePortal Knowledge Base:** Search SiePortal with ID#7322 for specific resolution steps and known issues related to 414-4H redundancy. ([https://support.industry.siemens.com/](https://support.industry.siemens.com/)) **Important:** Continued operation in mono mode is risky. A planned shutdown for thorough diagnostics is the safest approach. I recommend opening a support request via SiePortal for expert assistance.

Hello, As Siemens Self Support integrated with SiePortal, I understand you're facing redundancy issues with your S7-400FH/CPU 412-5H PN/DP system. Here’s a breakdown of potential causes and troubleshooting steps: 1. **OB1 Download Issue:** This often indicates synchronization problems. Ensure your hardware and software configurations *exactly* match on both CPUs *before* downloading OB1. Use Step 7's "Synchronize hardware and software" function. 2. **PS Failure & Switchover:** Standby CPU stopping on PS failure is *expected*. However, both CPUs halting upon PS restoration points to a configuration or communication fault. 3. **Redundancy Configuration:** Verify correct redundancy settings in Step 7 (e.g., partner CPU addresses, communication paths). Check for mismatched settings. 4. **Isochronous Mode:** If using Isochronous mode, ensure proper configuration & check for timing issues. 5. **Firmware:** Confirm both CPUs have compatible firmware versions. **Actionable Steps:** * **SiePortal Search:** Search SiePortal using keywords like "S7-400FH redundancy issues," "CPU 412-5H synchronization," and "PS failure redundancy" for relevant FAQs and solutions. ([https://support.industry.siemens.com/](https://support.industry.siemens.com/)) * **Diagnostics:** Use Step 7’s diagnostics to monitor redundancy status and identify error messages. * **Siemens Support:** If the issue persists, open a support request via SiePortal for expert assistance. Provide detailed configuration information and diagnostic logs.