156 Rockwell Automation Publication 1766-UM001O-EN-P - September 2021
Appendix C          Troubleshoot Your System
Figure 70 - Error Recovery Model
Analog Expansion I/O 
Diagnostics and 
Troubleshooting
Module Operation and Channel Operation
The module performs operations at two levels:
• module level
•channel level
Module-level operations include functions such as power-up, configuration, 
and communication with the controller.
Internal diagnostics are performed at both levels of operation. Both module 
hardware and channel configuration error conditions are reported to the 
controller. Channel over-range or under-range conditions are reported in the 
module’s input data table. Module hardware errors are reported in the 
controller’s I/O status file. See MicroLogix 1400 Programmable Controllers 
Instruction Set Reference Manual, publication 1766-RM001
 for more 
information.
Identify the error code and 
description.
Refer to page 206 for 
probable cause and 
recommended action.
Clear Fault.
Correct the condition 
causing the fault.
Return controller to RUN or 
any of the REM test modes.
Test and verify system 
operation.
Refer to page 206 for 
probable cause and 
recommended action.
Is the Fault 
LED on?
Is the RUN 
LED on?
Is the Power 
LED on?
Are the wire 
connections tight?
Tighten wire connections.
Does the 
controller have 
power supplied?
Check power.
Refer to page 206 for 
probable cause and 
recommended action.
Is an input LED 
accurately showing 
status?
Refer to page 206 for 
probably cause and 
recommended action.
Is the error 
hardware related?
Start
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
End
Yes
IMPORTANT From firmware revision 21.007 onwards, you can enable an automatic fault 
recovery mechanism to recover the controller from 2H, 4H, 8H and 9H error 
codes. For more information see Auto Reset Functionality on page 131.