SV0413 LSI Overflow fault in Fanuc drive

SV0413 LSI Overflow fault in Fanuc drive

Description

SV0413 is a logic counter overflow alarm. The servo system uses a "Error Counter" (LSI - Large Scale Integration chip) to track the difference between Command Pulse and Feedback Pulse. This counter has a maximum size (e.g., 32,767 pulses). If the error exceeds this buffer size, the counter wraps around or overflows, causing SV0413. This is similar to "Excess Error" but happens at the hardware register level.

Cause

• Sudden Stoppage: The axis hit a hard mechanical stop at high speed. The command kept going, but the motor stopped instantly, filling the buffer in milliseconds.
• Erratic Feedback: Noise on the encoder line created a burst of millions of pulses that flooded the counter.
• Gain Settings: If the parameters for the servo loop gain are wildly incorrect (too low), the error accumulates too fast for the CPU to empty the buffer.

Solution

1. Check Mechanics: Did the machine crash? Clear the obstruction.
2. Grounding: Check for noise on the feedback cable. LSI overflow is a common symptom of severe EMI.
3. Power Cycle: This alarm often latches hard. A full power down is required to reset the LSI registers.