SV0604 Communication Error (Amp to CNC) fault in Fanuc drive

SV0604 Communication Error (Amp to CNC) fault in Fanuc drive

Description

SV0604 is a high-level communication alarm usually found on Beta-series or I/O Link amplifiers. It indicates that the communication between the CNC and the amplifier was established but then lost during operation. Unlike FSSB alarms which are specific to optical rings, SV0604 often applies to amplifiers connected via I/O Link or older electrical serial interfaces.

Cause

• Cable Noise: The communication cable is routed too close to the high-voltage motor leads.
• Connector Vibration: The plug on the top of the Beta drive (JD1A/JD1B) is loose.
• Power Supply Dip: A momentary dip in the 24V control power caused the drive's CPU to reset, breaking the link.

Solution

1. Inspect JD1 Cable: Check the short ribbon cables or twisted pair cables linking the units. They are prone to cracking.
2. Check 24V: Monitor the 24V supply. If it dips when a large solenoid fires, it can reset the drive communication. Isolate the drive power supply from the solenoid power supply.
3. Ferrites: Add a ferrite core to the communication cable.