Allen-Bradley · PowerFlex 520-series Adjustable Frequency
An analog input, configured to fault upon signal loss, has detected the absence of its expected signal. This means the analog voltage or current signal from a sensor, potentiometer, or external controller is no longer present. This fault ensures the drive doesn't operate with an invalid or missing command signal.
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Measure the voltage or current signal directly at the drive's analog input terminals (e.g., X10/A1+, X10/A1-) using a multimeter to verify the external signal source is active and within range.
Inspect the analog input signal cable for continuity, proper shielding, and secure connections from the sensor/PLC to the drive terminals (e.g., X10).
Verify the analog input function parameters (e.g., P2-11 [AI1 Function], P2-13 [AI1 Min Level], P2-14 [AI1 Max Level]) are correctly configured for the expected signal type and detection threshold.
If using a current loop (e.g., 4-20mA), ensure the loop power supply is active and providing the necessary voltage to the sensor.
Temporarily connect a known good reference voltage or current source (e.g., 5VDC or 12mA) to the analog input terminals to confirm the drive's input circuit functionality.