How to replace the backup battery on an AB CompactLogix 5380 PLC
The CompactLogix 5380 battery alarm is straightforward: order the correct lithium battery, replace it with the controller powered on to preserve memory, and acknowledge the alarm. The battery typically lasts 5 to 7 years.
How to fix EtherNet/IP communication errors on an AB CompactLogix 5380
EtherNet/IP communication errors on a CompactLogix 5380 start with physical layer checks: cable, switch port, and IP address. Then check the Studio 5000 connection configuration for timeout and RPI settings.
How to replace a failed I/O module on an AB CompactLogix 5380 PLC
A failed I/O module shows a red fault LED and logs a fault code in Studio 5000. Note the slot number and module catalog number, go online with the PLC, inhibit the module, swap it, and re-enable it without modifying the program.
How to recover from program corruption on an AB CompactLogix 5380
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.
How to diagnose sensor reading drift on an AB CompactLogix 5380 analog input
Analog input drift is usually wiring noise or a loose field terminal. Measure the sensor signal directly at the field terminal and compare to the PLC tag value. If they differ, the I/O module or scaling is the issue. If the signal itself is noisy, fix the cable shielding.
How to diagnose unexpected shutdowns on an AB CompactLogix 5380 caused by power supply issues
Unexpected CompactLogix shutdowns almost always trace to the 24V DC power supply going out of regulation or an undervoltage event. Measure the 24V supply under load with an oscilloscope or data logger to catch the transient.