TL;DR

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.

What you might see

I/O module fault LED solid red
Studio 5000 or Logix Designer shows module fault in the I/O tree
connected field devices show no signal on that module
controller fault log shows 4xxx series I/O fault code

Likely causes

Tap to mark as ruled out

Module component failure from age or transient surge damage to I/O circuitry
Over-voltage on a field wiring terminal exceeding the module's input rating
Electrostatic discharge during prior maintenance damaging the module
Water or condensation contact with the module connectors

Required tools

Laptop with Studio 5000 Logix Designer (licensed, compatible version)
Ethernet cable for PLC connection
Replacement I/O module (exact catalog number match)
Insulated screwdrivers

Safety first

Field wiring on I/O modules can carry live process voltages (24V DC, 120V AC, or higher for analog modules). De-energize field circuits before handling wiring connectors.
Always inhibit the module in Studio 5000 before hot-swapping. Removing an active module without inhibiting can cause a controller major fault and trigger safety-critical outputs.

Procedure

8 steps · ~30 min

1
Open Studio 5000 Logix Designer, go online with the controller, and navigate to the I/O Configuration tree. Identify the slot number and the fault code for the failed module.[1]
2
Record the module catalog number from the tree and from the physical label on the module.
3
Check whether the module supports hot-swap by consulting the module manual. Many CompactLogix I/O modules support hot-swap without a controller fault.[1]
4
If hot-swap is supported: right-click the module in the I/O tree and select 'Inhibit Module'. Confirm the inhibit. This removes the module from the scan list.[1]
5
Remove the wiring connector from the module (disconnect block pulls off without removing wiring). Slide the module out of the chassis.
Warning: Even with the module inhibited, field wiring on the connector may carry live voltage from field devices. De-energize the field circuit before handling the wiring connector.
6
Insert the replacement module of the exact same catalog number into the same slot. Seat it firmly.
7
Re-attach the wiring connector.
8
In Studio 5000, right-click the module and select 'Uninhibit Module'. The controller will re-establish communication. Confirm the module status LED shows green.

Sources

Allen-Bradley CompactLogix 5380 Controllers User Manual (Pub 5069-UM001), Rockwell Automation (Allen-Bradley)
Allen-Bradley CompactLogix 5380 Controllers User Manual, I/O module replacement and inhibit procedures (general)
View source

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