Beckhoff TwinCAT 3 (XAR/XAE) with EtherCAT fault AL 0x0011: Invalid requested state change
The EtherCAT State Machine (ESM) defines which state changes are allowed; all others are refused with 0x0011, for example a request from OP directly to BOOT. Beckhoff lists it for P→S, I→O, P→O, O→B, S→B and P→B; the slave stays in its current state with the error flag set. Beckhoff’s solution: go step by step from the original state to the desired state.
Diagnose this with AI
Try Free PLC Fault Diagnostic Upload a keypad photo, the fault history or a parameter export from your Beckhoff TwinCAT 3 (XAR/XAE) with EtherCAT. InduQT compares the evidence and suggests the next useful checks.
When it happens
- During EtherCAT startup or a manual state change in the online view
- When the application sets slave states itself (e.g. FB_EcSetSlaveState)
Likely causes and checks
1Application or tool requests a jump the ESM does not allow (e.g. INIT directly to OP, or OP to BOOT)
- Points to it
- Error follows a state request from the PLC or a manual click in the online view.
- Check
- Trace which state was requested from which state; BOOT can only be reached via INIT.
2Slave fell back to a lower state while the master was still requesting the next step
- Points to it
- 0x0011 appears together with another AL status code shortly before.
- Check
- Read the logger for the first AL status code of that slave and fix that one first.
Telling it apart
- 0x0011 is a refused transition; 0x0012 is an unknown state code in AL Control.
- The real fault is often the code logged just before; 0x0011 alone usually points to the requesting application or tool.
Evidence to collect
- Logger export with the state change sequence
- Online tab State of the slave before and after
- PLC code that requests slave or master states
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