SV0457 Illegal Pulse Coder (Parameter) fault in Fanuc drive

SV0457 Illegal Pulse Coder (Parameter) fault in Fanuc drive

Description

SV0457 is a parameter/hardware mismatch alarm. It occurs when the "Motor ID" set in the digital servo parameters dictates a specific type of encoder (e.g., Serial Alpha 64i), but the drive detects a different type connected (e.g., Beta incremental). The system halts because the communication protocol required for the detected device differs from the configuration.

Cause

• Wrong Motor Installed: Maintenance replaced a motor with a "compatible" one that actually has a different encoder generation.
• Parameter Restore: Parameters were reloaded from an old backup that doesn't match the current machine hardware (e.g., after a retrofit).
• Cable Cross: Plugging the X-axis cable into the Y-axis motor (if they are different sizes).

Solution

1. Verify Part Numbers: Check the red cap on the motor. Read the type (e.g., A860-2000-T301).
2. Check Parameter 2020: Ensure the Motor ID entered corresponds to the motor actually installed.
3. Reset Par 2000: Sometimes toggling bit 1 of parameter 2000 (Pulse Coder Type initialization) forces the control to re-read the encoder data.