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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

704

I/O Fault

Fronius · Symo Advanced

What does 704 mean?

This status code indicates a fault with an external Input/Output (I/O) connected to the Fronius Primo GEN24 208-240 inverter, such as a relay or digital input. This can be caused by wiring issues, a faulty external device connected to the I/O, or an internal I/O circuit fault within the inverter.

Common Causes

  • Wiring issue to the relevant I/O terminals (e.g., loose connection, break, or short circuit).
  • The external device connected to the I/O (e.g., contactor for relay output, sensor for digital input) is faulty.
  • Incorrect I/O configuration settings in the inverter's parameters.
  • An internal I/O circuit fault within the inverter.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the wiring to the relevant I/O terminals (e.g., relay contacts, digital inputs) for proper connection and continuity.

  2. 2

    Test the external device connected to the I/O for functionality and ensure it is operating correctly.

  3. 3

    Verify the I/O configuration settings in the inverter's user interface to ensure they match the connected device and desired operation.

  4. 4

    De-energize the inverter (switch off AC and DC disconnects), wait for 5 minutes, then re-energize to reset. If the message persists, the inverter may require service.

Browse all codes in this manual (41)
Verified technical data. Last updated: April 2026

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Source: Fronius Symo Advanced
Open Manual (Page 149)Search more codes in this manual