What causes FANUC alarm 5198?

FSSB fiber optic cable is damaged, disconnected, or has a dirty connector between CNC and servo amplifier. Servo amplifier lost power or did not fully initialize before the CNC attempted to read ID data. Faulty or failing servo amplifier where the internal ID data chip or communication circuit has failed. Incorrect FSSB axis assignment or amplifier order does not match the parameter settings in the CNC. Loose or improperly seated fiber optic connector at either the amplifier or the CNC axis card.

How do I fix FANUC alarm 5198?

1. Power down the machine completely, then inspect all FSSB fiber optic cables for visible damage, sharp bends, or loose connections at both the CNC control card and each servo amplifier. 2. Clean the fiber optic connectors with a lint-free swab and confirm each connector clicks firmly into place, then power the machine back on to see if the alarm clears. 3. Check that all servo amplifiers are receiving proper control power and that their status LEDs show normal startup behavior before the CNC finishes booting. 4. If the alarm points to a specific axis, swap the fiber optic cable on that amplifier with a known good cable to rule out a cable fault. 5. Verify FSSB parameters (Param 1023, 1905, 1910-1919) match the physical amplifier order on the FSSB line, as a mismatch will prevent ID data from being read correctly. 6. If cable and power checks pass, the servo amplifier itself may have a failed communication circuit and should be replaced or sent for repair.

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FANUC Controller

Servo/Axis · Intermediate · 30-90 minutes

Alarm 5198

Fanuc Alarm 5198 - FSSB: ID DATA NOT READ

Alarm 5198 occurs when the CNC fails to read ID data from the servo amplifier during FSSB (Fiber Servo System Bus) initialization. This indicates a communication failure between the control and amplifier, typically caused by faulty FSSB cables, incorrect amplifier addressing, amplifier power issues, or defective amplifier hardware.

FANUCServo/AxisIntermediate30-90 minutes

5198

Fanuc Alarm 5198 - FSSB: ID DATA NOT READ

SERVO ALARM 5198

Root Cause Summary

Alarm 5198 occurs when the CNC fails to read ID data from the servo amplifier during FSSB (Fiber Servo System Bus) initialization. This indicates a communication failure between the control and amplifier, typically caused by faulty FSSB cables, incorrect amplifier addressing, amplifier power issues, or defective amplifier hardware.

Causes and Fixes

1
Power off the machine. Inspect FSSB fiber optic cables (JD1A/JD1B connectors) at both the amplifier and CNC control side for loose connections, visible damage, or contamination.
Do not look directly into fiber optic cable ends - can cause eye damage from laser light
2
Clean fiber optic connectors using lint-free swabs and optical-grade isopropyl alcohol. Check for bent or broken fiber tips under magnification.
3
Reseat all FSSB connections firmly. Ensure the cable routing has no sharp bends (minimum bend radius 30mm). Power on and check if alarm clears during initialization.
4
If alarm persists, substitute with known-good FSSB cable. Check DIAGNOSIS > FSSB screen to verify communication status and amplifier detection after cable replacement.

DIY Feasiblehigh confidence

Call a technician if:

·Multiple amplifier failures
·Repeated cable failures
·Parameter corruption with no backup

Prevention

Regular FSSB cable inspection
Maintain proper cable routing
Monitor amplifier power supply stability
Keep parameter backups current

Common Mistakes

Not checking control power before FSSB cables
Ignoring EMI sources near FSSB cables
Swapping amplifiers without parameter backup
Not verifying cable lock engagement

Related Alarms

5190 5191 5199 5200

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