FB ENVELOPE Value 4

Max Time Expired

Beckhoff · TwinSAFE Logic FB

What does FB ENVELOPE Value 4 mean?

The maximum allowed time for the SafeFunctionOut output to remain active has been exceeded within the FB Envelope function block. This indicates that the input value ('InValue') stayed within the 'Target Value' window for too long, or the configured 'Max Time (ms)' parameter was reached. This will force the output to switch off for safety.

Additional Steps

Steps 1–2 are listed in Priority Fix.

  1. 3

    Confirm that the 'SafeFunctionOut' output transitions to the safe state as expected when the fault occurs.

  2. 4

    Check for any external conditions, interlocks, or upstream logic that might inadvertently be holding 'InValue' within the target for too long.

Source: Beckhoff TwinSAFE Logic FB
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