F018
Invalid 1771 module response
Allen-Bradley · Logix 5000
What does F018 mean?
The 1771 module responded with an invalid message or data. This indicates a communication protocol issue or a fault within the 1771 module itself.
Common Causes
- The 1771 module response was not valid
Repair Steps & Checklist
Click steps to track your progress.
- 1
Inspect communication cabling between the Logix 5000 system and the 1771 module for damage, proper seating, and loose connections.
- 2
Verify status indicators on the 1771 module and any associated communication adapter for fault or error indications.
- 3
Measure the power supply voltage to the 1771 I/O rack or module against nominal specifications.
- 4
Check the Logix 5000 controller's configuration for the 1771 module, ensuring it matches the physical module type and addressing settings (e.g., DIP switches).
Verified technical data. Last updated: March 2026
Related Faults
Source: Logix 5000