Power-On Analog Value Check Error

What does GROUP Value 4 mean?

On startup, at least one analog TwinSAFE function block input deviates from its last saved value (Power-On Analog Value Check Error). This indicates an inconsistency in analog safety input signals during the system's power-on self-test, which could signify sensor drift, wiring issues, or faulty input modules. This prevents the system from starting safely.

• Analog sensor value changed significantly during power-off (e.g., a fluid level dropped) and deviates from its last saved value at power-on.
• Incorrect 'Power-On Check Tolerance' parameter (e.g., P8-01) set too low, causing normal startup deviations to be flagged as errors.
• Faulty analog sensor providing an unstable or incorrect reading immediately after power-up.
• Electrical transient or noise on the analog input line during module power-up, causing a momentary incorrect measurement.

Click steps to track your progress.

1. 1

   1. Verify the actual analog process value (e.g., pressure, temperature) against the expected startup value before powering the module.

2. 2

   2. Review the 'Power-On Analog Value Check' configuration, specifically the deviation tolerance parameter (e.g., P8-01) and delay.

3. 3

   3. Calibrate or replace the analog sensor if it exhibits unstable or inaccurate readings upon power-up.

4. 4

   4. Ensure that the analog input signal is stable and within its expected range (e.g., 4-20mA loop) when the safety module powers up.

5. 5

   5. Check for proper grounding and shielding of the analog input cables to prevent power-on transients.