Greetings everyone, I have an intriguing puzzle with a historical twist and I am seeking insights or resolutions. Here's the background story: I acquired a 1769-L33ERMS from a previous owner who intended to use it for production but opted for a more budget-friendly PLC instead. This PLC was operating on the V36 firmware, a version unfamiliar to the machines on the production floor or to many of us. Upon receiving it, I made the decision to downgrade its firmware to V35, a known stable version that is compatible with multiple machines using Logix. The downgrade process appeared successful with all blocks downloaded and the log showing a successful update. However, when ControlFlash attempted the power cycle sequence and "poll on powerup" response, the PLC failed to restart and displayed solid red lights. Without wanting to incur additional costs, I decided to explore the internal components and discovered a hidden button on the board near the mode switch. Pressing this button during powerup triggered a series of power cycles indicated by the LEDs, eventually bringing the controller back online. Despite this success, the PLC now experiences a safety task fault every time it is power cycled, specifically Type 14 code 07: Safety Task Inoperable fault, resulting in a program dump. Only a complete re-download of the program resolves this issue. I have attempted various troubleshooting methods including downloading different programs tailored for this controller and version, creating a new program specifically for the L33ERMS running V35, power cycling the controller in different switch modes, enabling time synchronization, and adjusting the Safety Task scan period. However, all these efforts yield the same outcome. I am open to suggestions or solutions to address this persistent fault. While another firmware change may be considered as a potential next step, I am cautious due to previous challenges encountered. Your input and expertise are greatly appreciated. Thank you!
I am curious about the age of the PLC, as I have noticed that newer models are being sold with a label recommending the use of firmwarexx or newer versions. Have you attempted to reinstall version v36 to see if it resolves the issue you are experiencing?
One user inquired about the age of the PLC, mentioning that newer models come with a label specifying the minimum firmware version required. It was suggested to try reloading version v36 to address any issues. However, considering the age of the PLC, which is likely around 7 years old, and past update challenges, reloading v36 is seen as a last resort. Exploring all possible solutions before attempting another firmware update is preferred.
If the device is old, there should be no issues with the firmware limit. Consider re-flashing to V35 to ensure the update was successful.
User alan_505 suggested considering re-flashing the firmware to V35 to ensure that the update was fully installed on the old device. This can be a solution if the current firmware version has limitations. If that doesn't work, exploring other options that haven't been attempted yet is also a possibility before resorting to a firmware update as a last resort.
How reliable is the onboard memory backup? It appears that the program is being lost during power cycles.
Hi there, first off, kudos for your tenacity in attempting to troubleshoot this issue on your own. Type 14 code 07 faults can definitely be a headache! I faced a similar situation a few years ago and what helped was checking the safety signature of the safety task. If this signature doesn't match the one that was there when the safety task was last toggled to RUN mode, it triggers the fault you're experiencing. This could have been affected during your downgrade. If you've restructured any part of the safety code or modified any safety I/O configurations, it changes the safety signature and might be causing the fault. You might want to compare the current safety signature with a saved close-copy. If they aren't matching, try adjusting your safety tasks accordingly. I hope this helps!
From your detailed explanation, it seems like you've done extensive troubleshooting already, which make this a tough nut to crack. However, considering that the fault is a Safety Task Inoperable, I suspect that this could be tied to the Safety Signature of your programs. Each safety program stored in the Logix has a unique signature to verify its integrity, and if it's mismatched somehow due to the downgrade, a safety fault can occur. Even though you've tried to download various programs, they could still have this issue if they were not properly recreated for V35. I would suggest trying to create a completely new safety program from scratch specifically for V35, rather than modifying an existing one. Make sure to fully delete the existing one before downloading the new. If the problem persists, you might have to consider a firmware upgrade, despite the resistance to do so.
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Answer: Answer: The safety task fault (Type 14 code 07) may occur due to a firmware downgrade causing incompatibility issues with the safety tasks. This fault results in a program dump and requires a complete re-download of the program to resolve.
Answer: Answer: You can try troubleshooting methods such as downloading different programs tailored for the controller and firmware version, creating a new program specifically for your PLC running V35, power cycling the controller in different switch modes, enabling time synchronization, and adjusting the Safety Task scan period. If the issue persists, seeking expert advice or considering another firmware change may be necessary.
Answer: Answer: If your PLC displays solid red lights and fails to restart after a firmware downgrade, you can try pressing the hidden button near the mode switch during powerup to trigger a series of power cycles, which might bring the controller back online. If this does not resolve the issue, further troubleshooting and potentially seeking professional assistance may be required.
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