TL;DR

Program corruption shows as a major fault on power-up or a checksum error in the fault log. Restore from the latest validated ACD backup in Studio 5000 or from the SD card if auto-restore was configured.

What you might see

controller shows major fault on power-up with code 0x0004 or similar checksum fault
controller enters faulted state and cannot be cleared without restore
program tasks are missing or modules show incorrect configuration
Studio 5000 reports project version mismatch on going online

Likely causes

Tap to mark as ruled out

Power loss during a program download operation corrupting the flash memory
Memory fault on the controller module from age or a transient event
Unintended program modification downloaded without proper change management
SD card file system error during an auto-save cycle

Required tools

Laptop with Studio 5000 Logix Designer (licensed)
Validated ACD backup file (version controlled)
SD card (if restore from card is planned)
Ethernet cable

Safety first

Downloading a program to a controller on a running process can change output states and cause unexpected machine motion. Always put the machine in a safe state before initiating a download.
Do not download an unvalidated or unknown-revision program file. A wrong program version can cause a safety or process incident.

Procedure

7 steps · ~45 min

1
Read the fault code in Studio 5000 Controller Properties, Fault Log tab. Record the exact fault code and description before any action.[1]
2
Check the SD card if one is installed. On the EMCP keypad or in Studio 5000, attempt an SD card load operation: Store/Load controller menu.[1]
3
If the SD card load succeeds, the controller will return to normal. Verify the loaded program version matches the approved revision on the nameplate or maintenance log.
4
If no SD card or the SD card is also corrupted, obtain the latest validated ACD (Studio 5000 project file) backup from your change management system. Confirm the file revision is the correct approved version.
Warning: Do not download a program file of unknown revision to a controller on an active process. Confirm the file with your controls engineer before downloading.
5
Clear the major fault in Studio 5000 (Controller Diagnostics, clear fault). If the fault does not clear, cycle power to the controller.
6
Go offline in Studio 5000, open the validated ACD file, and select Download. Follow the download prompts. The controller will switch to Program mode during the download.[1]
7
After download completes, go online and verify the program is running correctly. Test all critical I/O points before releasing the machine to production.

Sources

Allen-Bradley CompactLogix 5380 Controllers User Manual (Pub 5069-UM001), Rockwell Automation (Allen-Bradley)
Allen-Bradley CompactLogix 5380 Controllers User Manual, SD card restore and program download procedures (general)
View source

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