Safety Task Fault Type 14 Allen-Bradley — Safety module F-CPU/F-DI/F-DO in passivation
At a glance
- Severity
- FAULT STOP
- Domain
- PLC
- Reference standard
- IEC 62061 / IEC 61508 SIL3
- Product / context
- Guard I/O Safety Fault — 1756-L7SP GuardLogix
What it means
A safety module (F-module) has entered passivation state: the safety I/O values are replaced with safe values (typically 0). This occurs when the safety system detects an inconsistency between redundant channels, a PROFIsafe communication error, or a hardware fault in the F-module. The machine stops because safety consents are removed.
Probable causes
- Discrepancy between the two redundant channels of a safety input (e.g., only one E-Stop contact opened).
- PROFIsafe communication error: timeout, CRC error, or duplicate F-address on the network.
- Incorrect wiring on F-DI inputs: test pulse sensor not connected or incorrectly connected.
- Safety parameters (F-Address, F-WD Time) inconsistent between the configuration and the physical module.
Where to start
Identify the passivated F-module from the online diagnostics (in TIA Portal: Safety Administration, in Studio 5000: Safety Task Faults). Does the module report a PROFIsafe/CIP Safety communication error?
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the five IndexOS apps: free, works offline.
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The same fault on other brands
More Allen-Bradley codes
- 1756-IB16 — Digital input module — input not reading (stuck at 0)
- 1756-IF8 — Analog input module — full-scale reading or error
- 1756-PA75 — Unstable PLC power supply — cyclic restarts
- Major Fault Type 1 — CPU in STOP
- Major Fault Type 3 — CPU ↔ I/O module communication error (backplane bus)
- Minor Fault Type 10 — Memory error / backup battery depleted