Measurement underflow at the I/O module

¿Qué significa 7 ?

The input signal measurement at the I/O module has fallen below its minimum measurable range (underflow). This indicates that the sensor input is providing a value lower than the module can process, potentially leading to incorrect or invalid safety-related readings.

• The connected sensor is outputting a signal (voltage or current) that is below the minimum input range of the I/O module channel (e.g., a 0.5V signal connected to a 1-5V input).
• An open circuit in the sensor wiring or a loose connection at the I/O module terminals (e.g., AI+, AI-), leading to a near-zero or floating input.
• Malfunction of the connected sensor, causing it to output an abnormally low or zero signal even when active.
• Incorrect I/O module input type configuration in the engineering software (e.g., configured for 1-5V when a 0-10V sensor is connected that currently outputs 0V, Parameter P3-01).
• Improper scaling factor or offset parameter set in the PLC program for the analog input, causing an apparent underflow in the interpreted value.

Haga clic en los pasos para seguir su progreso.

1. 1

   Using a calibrated multimeter, measure the actual analog signal (e.g., voltage across AI+, AI- or current in series) from the sensor at the I/O module terminals.

2. 2

   Compare the measured signal value with the specified minimum input range of the I/O module's analog input channel (refer to module datasheet).

3. 3

   Perform a continuity test on the signal cable from the sensor output to the I/O module terminals to detect any open circuits or high resistance.

4. 4

   Verify the I/O module's channel configuration in the PLC engineering software (e.g., Parameter P3-01 for input range) matches the connected sensor's output specifications.

5. 5

   Isolate the sensor and test its output independently to ensure it is not malfunctioning and sending an abnormally low signal.