CPU fault

What does E.7 mean?

This is a CPU fault that stops the inverter output when a communication fault occurs within the built-in CPU. Specific causes include excessive electrical noise or a short circuit between the PC and SD terminals. This critical internal error prevents safe operation.

• Severe electrical noise or electromagnetic interference (EMI) affecting the CPU's internal bus or external communication circuits.
• Direct short circuit between the PC communication port and the 'S' signal terminal (typically a common ground or reference).
• Damage to the communication interface components on the control board (e.g., transceivers, opto-isolators).
• Software or firmware bug causing an unhandled exception within the CPU's communication routine.
• Voltage transient or power surge affecting the inverter's control power supply.

Click steps to track your progress.

1. 1

   Disconnect all external communication cables and devices from the inverter's serial ports (e.g., RS-485 terminals S, RDA, RDB).

2. 2

   Power cycle the inverter by fully removing main AC input power for at least 60 seconds, then reapply power.

3. 3

   Use a multimeter to measure continuity or resistance between the 'PC' and 'S' terminals to rule out a direct short circuit.

4. 4

   Verify proper grounding of the inverter chassis and all connected equipment to minimize common mode noise.

5. 5

   Check the inverter's internal diagnostic LEDs (if available) for any additional fault indications or status codes.