InValue Expired (Negative)

What does 0x40C8 mean?

The input value (InValue) has expired, and its current state is below zero. This suggests that the input signal has either become invalid or has dropped below its expected range, leading to a safety state. The fault provides the FB instance, the current InValue, and the MinAllowedValue for detailed diagnosis.

• Complete loss of input signal (e.g., 4-20mA sensor with broken wire resulting in 0mA) causing a sub-zero or underflow reading.
• Sensor malfunction where its output consistently falls below its specified minimum range (e.g., 0VDC from a 0-10V sensor).
• Incorrect offset or scaling applied to the analog input, causing valid readings to be interpreted as negative (e.g., parameter P3-01).
• Faulty analog input module channel (e.g., EL3xxx channel 1) reading below its defined input range.

Click steps to track your progress.

1. 1

   1. Measure the voltage or current at the analog input terminals (e.g., AI_A) of the safety module.

2. 2

   2. Verify the sensor's output (e.g., 4-20mA, 0-10V) directly at the sensor terminals.

3. 3

   3. Check the scaling and offset parameters (e.g., P3-01, P3-02) in the TwinSAFE configuration for the analog input.

4. 4

   4. Inspect the input signal wiring for open circuits, loose connections, or damaged shielding.

5. 5

   5. Replace the sensor if its output remains below the valid range even when the process value is acceptable.