Max Time Expired

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.

• Process variable remaining within the 'Target Range' (e.g., InValue between P2-01 and P2-02) longer than allowed by the configured 'Max Time'.
• Incorrect 'Max Time' parameter (e.g., P2-03) set too short for the normal operational dynamics of the process.
• Sticking or faulty sensor causing the 'InValue' to hold a constant reading within the 'Target Range'.
• External logic or process condition preventing the 'InValue' from exiting the 'Target Range' (e.g., valve failing to open).

Click steps to track your progress.

1. 1

   1. Analyze the process data (e.g., via HMI trend, oscilloscope) to confirm 'InValue' is indeed remaining within the defined 'Target Range'.

2. 2

   2. Review and adjust the 'Max Time' parameter (e.g., P2-03) in the FB Envelope configuration to match process requirements.

3. 3

   3. Inspect the sensor and actuator (if applicable) associated with 'InValue' for mechanical issues or sticking.

4. 4

   4. Verify all conditions that are supposed to drive 'InValue' outside the 'Target Range' are functioning correctly.

5. 5

   5. Check for any interlocks or external signals that might be inadvertently holding the 'InValue' within the target range.