Over/Undervoltage Detected

What does E2-48 mean?

The Safety PLC has detected an abnormal power supply voltage condition (either too high or too low). This can lead to unstable operation or damage to the PLC components, compromising reliability.

• Input supply voltage (e.g., 24VDC to the PLC module) is consistently below the minimum allowed operating voltage (e.g., 21.6VDC).
• Input supply voltage (e.g., 24VDC to the PLC module) is consistently above the maximum allowed operating voltage (e.g., 26.4VDC).
• Fluctuations or transients in the 24VDC power supply caused by other high-current loads switching on/off rapidly, resulting in temporary sags or spikes.
• Incorrectly rated or failing power supply unit (PSU) for the total current draw of the Safety PLC and its connected I/O, leading to voltage sag under load.
• Loose or corroded power wiring connections to the Safety PLC's input terminals causing intermittent voltage drops or overvoltage conditions.

Click steps to track your progress.

1. 1

   1. Using a calibrated multimeter, measure the 24VDC supply voltage directly at the power input terminals of the SM560-S Safety PLC.

2. 2

   2. Monitor the 24VDC supply voltage with a logging multimeter or oscilloscope over a period, checking for transient sags below 21.6VDC or spikes above 26.4VDC.

3. 3

   3. Inspect and tighten all 24VDC power wiring connections from the power supply unit to the Safety PLC and to any connected I/O modules (e.g., Terminal X1).

4. 4

   4. Verify the power supply unit's (PSU) output voltage and current rating, ensuring it is adequately sized for the total connected load; replace if undersized or failing.

5. 5

   5. Implement a power conditioning solution (e.g., surge suppressor, uninterruptible power supply (UPS) for control power) if external power grid instability is suspected.