When the Fanuc system detects that it cannot maintain normal system operation, it will transfer to the system alarm screen.
When entering the system alarm state, the system will:
Disconnect the excitation of the servo and spindle amplifier
Disconnect the communication of the I/O LINK
When a system alarm occurs, it switches to the screen shown below. This screen is called the system alarm screen


System alarms can be divided into the following 3 types.

Alarms detected by software
Alarms detected by hardware
Other alarms

Alarms detected by software
The CNC system software mainly detects software anomalies.
Typical causes of anomalies are:
Detection of processing/data inconsistencies based on internal status monitoring software
Access outside the data/command range
Division by zero
Stack overflow
Stack underflow
DRAM and number check error

Alarms detected by hardware mainly detect hardware anomalies by hardware.
Typical abnormal reasons are:
Parity error (DRAM, SRAM, ultra-high-speed cache)
Bus error • Power alarm
FSSB cable disconnection 3 other alarms Other reasons are:
Alarms detected by peripheral software
Servo software (watchdog, etc.)
PMC software (I/O LINK communication abnormality, etc.)

Detection of abnormal power supply of the nth servo amplifier Cause of failure: Focus on checking the power supply of the amplifier, check whether the 24V power supply voltage is normal, check whether there is an external short circuit, etc.