Troubleshooting: Triconex Active & Standby LEDs Flashing Together
When both the Active and Standby LEDs on a Triconex processor are flashing, it is a critical warning. It means the controller cannot decide its role. This state prevents the system from achieving a stable, fault-tolerant condition. Immediate action is required.
What the Flashing LEDs Mean
In a healthy Triconex system, one processor is Active (solid green) and the other is Standby (solid amber). When both flash, the processors cannot agree on which one should be in charge. The system is in an undecided state and is not fully operational.
Most Common Causes
- Firmware Mismatch: This is the #1 cause. The two processors have different firmware versions installed.
- Application Mismatch: The application program or its CRC (checksum) is not identical on both processors.
- Improper Installation: The new processor module was inserted while the system was powered on (“hot-swapped”) without following the correct procedure.
- Hardware Connection Issue: A faulty backplane connection, bent pins, or the module not fully seated in the chassis.
- Corrupted Memory: Non-volatile memory (NVRAM) corruption on one of the processors.
Step-by-Step Resolution Guide
- Power Down Properly: If safe to do so, perform a complete power cycle of the Tricon chassis. This can clear a temporary arbitration lock.
- Check Firmware: Using TriStation or similar software, verify the firmware version on both processor modules. They must be exactly the same.
- Verify Application: Ensure the exact same application program is loaded on both processors. Check the CRC values match.
- Inspect Hardware: Power down the chassis. Reseat both processor modules firmly. Inspect the backplane connector for damage or debris.
- Replace/Reinstall: If one module is suspected faulty, replace it with a known-good spare that has the correct, matching firmware.
Critical Best Practices
- Never Hot-Swap Processors Casually: Replacing a main processor is a major activity. Follow the manufacturer’s detailed procedure, which usually involves downloading the application and power cycling.
- Manage Your Spares: Label all spare processor modules with their exact firmware version. Never assume a spare is compatible.
- Synchronize Before Operation: After any change, use the software tools to force a synchronization check between the processors.
Example: Fixing a Firmware Mismatch
A plant inserted a spare processor, causing both LEDs to flash. Diagnostics showed the running system used firmware v10.3, but the spare had v10.5. Technicians reloaded v10.3 onto the spare module. After a power cycle, one processor became Active (solid green) and the other Standby (solid amber), resolving the issue.
Frequently Asked Questions (FAQ)
Diagnostic Questions
- Can the system still protect the process in this flashing state?
No. The system’s fault tolerance is compromised. It may not be able to perform a proper bumpless transfer if a fault occurs. Consider it in a degraded state. - Is it okay to just ignore it if the process seems to be running?
Absolutely not. This is a major diagnostic warning. The system is not in its designed, safe state. You must resolve it.
Technical Procedure Questions
- How do I check the firmware version?
Connect to the Tricon system with the TriStation software. Navigate to the hardware diagnostics or module properties to see the firmware details for each processor. - What if reseating and power cycling don’t work?
The next step is to use the software to reload the application program to both processors, ensuring they are identical. If the problem persists, one of the processor modules or the chassis backplane may be faulty.
Prevention Questions
- How can we prevent this during maintenance?
Create a strict procedure for processor replacement. The procedure must include steps to verify firmware compatibility and to perform a controlled shutdown/restart of the chassis.
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