Sensor Voltage Too Low

What does E3-16175 mean?

The sensor voltage detected on the I/O bus module is below the acceptable threshold. This indicates a potential issue with the power supply to the connected sensors or a fault within the sensors themselves, leading to inaccurate readings or complete sensor malfunction and unreliable process control.

• External sensor power supply failure or overload, drawing excessive current and causing a voltage drop below 20VDC.
• Open circuit or high resistance (e.g., >5 Ohms) in the wiring between the sensor's power terminal and the I/O module's sensor input (e.g., broken wire, corroded terminal).
• Faulty sensor drawing too much current (short circuit to ground) or internal damage causing excessive voltage drop.
• I/O module's internal sensor excitation power supply failing or experiencing a brownout condition.
• Insufficient sizing of the common external power supply for multiple sensors, leading to cumulative voltage sag when all sensors are active.

Click steps to track your progress.

1. 1

   1. Measure the voltage directly at the sensor's power terminals (e.g., +24V to GND) using a multimeter.

2. 2

   2. Verify the voltage at the corresponding sensor input terminal on the I/O bus module (e.g., terminal 10 for AI1) against the module's specifications.

3. 3

   3. Isolate the problematic sensor by temporarily disconnecting it from the I/O module and observe if the fault clears for other sensors.

4. 4

   4. Inspect the power supply for the sensors, measuring its output voltage and current draw, ensuring it's not overloaded and its output is stable.

5. 5

   5. Check for continuity and resistance in the sensor's power cabling from the power supply to the sensor and then to the I/O module's input. A reading above 2 ohms is suspect.