SP9024 (Alarm 24) Serial Transfer Error (Spindle) fault in Fanuc drive

SP9024 (Alarm 24) Serial Transfer Error (Spindle) fault in Fanuc drive

Description

SP9024 (Alarm 24) indicates a breakdown in the serial communication specifically between the CNC and the Spindle Amplifier. Unlike FSSB (Optical), older or non-optical spindle drives use an electrical serial cable. This alarm means the "Heartbeat" signal from the CNC to the Spindle drive has stopped. The spindle drive shuts down because it is no longer receiving commands.

Cause

• Cable Failure: The electrical serial cable (often a customized Honda connector cable) is broken or has a loose shield.
• CNC Lockup: The Main CPU of the CNC has frozen or crashed, stopping the data stream.
• I/O Link Module: If the spindle is connected via I/O Link, the interface module may have failed.

Solution

1. Check CNC Status: Is the CNC screen frozen? If the CNC crashed, Alarm 24 is just a symptom. Reboot the machine.
2. Inspect Cable: Check the cable connecting the CNC Spindle Port to the Drive (JY1). Look for corrosion or loose screws.
3. Grounding: Ensure the Spindle Drive chassis is bonded to the CNC chassis. Ground potential differences can kill the serial driver chips.