SV0424 Digital Servo Data Invalid fault in Fanuc drive

SV0424 Digital Servo Data Invalid fault in Fanuc drive

Description

SV0424 is a communication initialization alarm. It indicates that the data sent from the CNC's axis card to the servo amplifier during the boot-up sequence was corrupt or missing essential configuration blocks. Unlike FSSB alarms (which are optical breaks), this is a data protocol error. The drive exists, the light is working, but the "packets" of information (parameters, startup instructions) made no sense to the drive's CPU.

Cause

• Module Mismatch: The axis card software version is incompatible with the servo amplifier firmware version. This happens after upgrading a CNC or replacing a drive with a much newer version.
• Noise on Ground: Severe ground loops can corrupt the data packets during the sensitive boot phase.
• Axis Card Failure: The DSP (Digital Signal Processor) on the CNC axis card is failing.

Solution

1. Reseat Cards: Power down, remove and re-insert the Axis Control Card on the CNC mainboard. Oxide on the contacts can cause this.
2. Check Grounding: Ensure the CNC chassis and the Drive chassis share a solid, low-resistance ground connection.
3. Firmware Check: If you replaced a drive, check the ROM version written on the chip/sticker. Consult Fanuc to see if it requires a CNC software patch.