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ErrorLib — Industrial Fault Code Library

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2-1-2-1

Max Supply Voltage μC1 Exceeded

Beckhoff · EL1904 Digital Input Terminal

What does 2-1-2-1 mean?

The supply voltage to microcontroller 1 (μC1) within the EL1904 terminal has exceeded its maximum permissible limit. This overvoltage condition can stress internal components and potentially lead to permanent damage to the microcontroller.

Common Causes

  • External power supply voltage exceeds the maximum allowable threshold for μC1.
  • Power surge or transient event on the supply line.
  • Incorrect voltage regulator setting for μC1.
  • Component failure within the power conditioning circuitry for μC1.
  • Mains voltage fluctuation beyond operational limits (P2-1).

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Measure the supply voltage at the terminal's power input using a multimeter.

  2. 2

    Verify the measured voltage is within the specified operating range for the terminal (refer to technical data for specific values).

Browse all codes in this manual (6)
Verified technical data. Last updated: April 2026

Related Faults

3-1-2-1Max Supply Voltage μC2 Exceeded4-1-2-1Min Supply Voltage μC1 Not Met5-1-2-1Min Supply Voltage μC2 Not Met
Source: Beckhoff EL1904 Digital Input Terminal
Open Manual (Page 40)Search more codes in this manual