1769-L16-B1BB Unrecoverable Fault, HELP

yildrim88

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Join Date
Sep 2021
Location
New York
Posts
3
Dear all,

First post on the forum.

my supervisor and I have a 1769-L16-B1BB acting up in the field. We decided to program and send an identical replacement unit. We assembled a processor and expansion module at our facility, identical to problematic system in the field. As far as we know straight from the box factory fresh. I connected to the processor via Ethernet and downloaded the same program. Studio 5000 prompted me to update the firmware, which I did. From what I saw the download transferred all four blocks. However, when the software switched to poll on start-up, the connection timed out and the process aborted. While the processor continued to appear on both my RSlinx Ethernet and Ethernet/IP drivers, I was unable to connect.

When my supervisor check the status light on the processor, the ok light was a solid red. From what understand that signals an unrecoverable fault. My supervisor cycled power, no effect. Then he tried resetting the unit by pressing the reset button (with a paperclip) while cycling power, no effect:confused:.

Due to the critical nature of the situation we pull our second and last processor from stock. Assembled it with the expansion module and connected via Ethernet. The exact same thing happened. As of right now we have two controllers with non-recoverable faults in addition the one faulting in the field. Long story short we are out of ammo and at a loss.
 
Has anyone experience something similar? I have programmed more than a few CompactLogix systems. I don't think I did anything different then what I usually do. One bad controller is unlikely, two bad is astronomically rare. What did I do wrong?
 
I don't remember all the details, but had a similar problem with a 1769-L24ER. Another guy went to the customers, did something, not sure what???


The processor would not allow an Ethernet connection, so I tried the USB port and it worked, then the Ethernet worked.



Might not be anything related to your issue.


EDIT: I might add I downloaded my version of the program via USB, then it worked.
 
Last edited:
Has anyone experience something similar? I have programmed more than a few CompactLogix systems. I don't think I did anything different then what I usually do. One bad controller is unlikely, two bad is astronomically rare. What did I do wrong?

Well, as others might think, there are options, if you were standing in front of it. You could adjust the firmware level up or down, inhibit I/O , research the FAULT CODE and location.
Remotely, not so much.
 
Normally, I would agree but the second two didn't make it past the firmware update. I don't think the program was ever downloaded.

Thank you, I am going to try to get a USB cable and connect.
 
I'd bet a pint of my favourite beer that both times you forgot to set a static IP address in the PLC before flashing it.

Out of the box, the CLX's are configured for DHCP. If you flashed the firmware over ethernet, you no doubt used the DHCP utility (or similar) to give it an IP address first, then flashed the firmware.

The problem with this, if my suspicion is correct, is that while you gave it an IP address, you didn't disable DHCP. So the next time the CLX is power cycled, it will again revert back to DHCP.

What this means is that you downloaded all of the firmware blocks to the CLX, and it then rebooted to complete the process. ControlFlash (or ControlFlash Plus) waited for it to come back online to confirm that the firmware update was successful, but it never did, because when it powered back up, it powered up without an IP address again.

The good news is (again, assuming I'm right about this) that your PLC's are probably fine. They got the whole firmware update - it's just that ControlFlash couldn't see it to confirm. If you give them an IP address again, you'll probably see that the only reason they have the red OK light is because there's no program in them.

It's for this reason that I always, always, always power cycle any device immediately before performing a firmware upgrade. Just to make sure that if it needs to power cycle at any point throughout the update, it's not going to cause any issues like this when it does.
 

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