STO input mismatch (_ecSTO_INPUT_MISMATCH)

What does 10035 mean?

The drive has detected an inconsistency in its internal Safe Torque Off (STO) registers, meaning the two redundant STO inputs are not in the same state. This is a safety fault that can occur whether the drive is enabled or disabled, indicating a potential failure in the safety circuit or a timing issue, which compromises the STO function.

• One of the two redundant STO input signals (e.g., STO_IN1, STO_IN2) transitions state (e.g., from 24VDC to 0VDC) significantly before or after the other.
• Asynchronous operation of external safety relays or contacts supplying the two STO inputs, leading to a momentary state difference.
• A wiring fault or intermittent connection on only one of the STO input terminals (e.g., a loose wire at X12.1 but not X12.2).
• Interference (e.g., EMI) affecting only one of the STO input signal lines, causing a momentary false transition.
• Internal timing discrepancy or component tolerance drift within the STO monitoring circuit of the drive.

Click steps to track your progress.

1. 1

   Using a dual-channel oscilloscope, monitor both STO input signals (e.g., STO_IN1 at X12.1 and STO_IN2 at X12.2) simultaneously to identify any timing discrepancies during state changes.

2. 2

   Inspect the wiring to both STO input terminals (e.g., X12.1 and X12.2) for any loose connections, damaged insulation, or incorrect termination.

3. 3

   Test the external safety relays or contactors (e.g., K1, K2) providing the STO signals for consistent and simultaneous opening/closing of their contacts.

4. 4

   Ensure adequate shielding for the STO input cables, and route them away from power cables or sources of high electromagnetic interference (EMI).

5. 5

   Confirm that the drive's STO configuration parameters (if any, e.g., P10-01 (STO Delay Time)) are set appropriately for the application and safety component response times.