E1

DO (B0 to B7) Common Abnormal Voltage

Fanuc · Connection and Maintenance

What does E1 mean?

This alarm indicates an abnormal voltage condition detected on the common line for digital outputs B0 through B7. This typically signifies an issue with the power supply providing voltage to this group of outputs, or a fault within the connected wiring or load. When active (bit E1 is '1'), the CNC will either issue a status alarm (for I/O Link i) or set a specific bit in the DI area (for I/O Link) to indicate the abnormal state.

Repair Steps

  1. 1

    Measure the supply voltage at the terminal connected to the DO (B0-B7) common. Verify this voltage is stable and within the specifications for the digital output module.

  2. 2

    Visually inspect the wiring and connections for the DO (B0-B7) common and its loads for any signs of damage, shorts, or loose terminations.

  3. 3

    If multiple external loads share this common, systematically disconnect them one by one to determine if a specific load or its wiring is causing the voltage abnormality.

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Verified technical data. Last updated: March 2026
Source: FANUC Connection and Maintenance