What causes FANUC alarm 5134?

Damaged or disconnected FSSB optical fiber cable between CNC and servo amplifier. Servo amplifier not receiving proper 24V DC control power during startup. Faulty or failing servo amplifier that is not responding to initialization handshake. Incorrect FSSB parameter settings after amplifier replacement or system configuration change. Dirty or damaged optical fiber connectors causing signal loss on the servo bus.

How do I fix FANUC alarm 5134?

1. Power down the machine and inspect all FSSB optical fiber cables for visible damage, kinks, or loose connections at both the CNC control end and each servo amplifier. 2. Check that the servo amplifier cabinet has proper 24V DC control power and that all amplifiers show their ready indicator lights during power-up sequence. 3. Clean the optical fiber connectors on both ends using a proper fiber optic cleaning kit, then reseat all connections firmly before powering back on. 4. If a specific amplifier is suspect, check the FSSB alarm diagnostics on the CNC screen to identify which axis or amplifier in the chain is failing to respond. 5. Verify FSSB parameters (typically around parameter 1023 and 1905 series) match the physical amplifier configuration, especially if any hardware was recently replaced. 6. If all cables and power check out, swap the suspect amplifier with a known good unit to confirm whether the amplifier itself has failed.

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FANUC Controller

Servo/Axis · Intermediate · 30-90 minutes depending on root cause

Alarm 5134

Fanuc Alarm 5134 - FSSB: OPEN READY TIME OUT

Fanuc alarm 5134 FSSB OPEN READY TIME OUT occurs when the CNC fails to establish communication with one or more servo amplifiers via the Fanuc Serial Servo Bus during power-up initialization. The servo amplifier did not transition to READY state within the timeout period, typically caused by FSSB optical fiber cable issues, amplifier power supply problems, or amplifier hardware failure.

FANUCServo/AxisIntermediate30-90 minutes depending on root cause

5134

Fanuc Alarm 5134 - FSSB: OPEN READY TIME OUT

SERVO ALARM 5134

Root Cause Summary

Fanuc alarm 5134 FSSB OPEN READY TIME OUT occurs when the CNC fails to establish communication with one or more servo amplifiers via the Fanuc Serial Servo Bus during power-up initialization. The servo amplifier did not transition to READY state within the timeout period, typically caused by FSSB optical fiber cable issues, amplifier power supply problems, or amplifier hardware failure.

Causes and Fixes

1
Check all FSSB optical fiber cable connections at the CNC (JD1A, JD1B) and amplifier connectors (JL1A/JL1B for loop topology). Ensure connectors are fully seated and locking tabs engaged.
2
Inspect fiber optic cable ends for contamination, cracks, or physical damage. Clean with approved optical cleaning tools (lint-free swabs and isopropyl alcohol). Replace any damaged cables with Fanuc-specified FSSB cables.
Never look directly into fiber optic connectors when system is powered. Laser light can cause eye damage.
3
Navigate to DIAGNOSIS > FSSB (screen varies by series: often DIAGNOSIS 200-209 for axis data). Check FSSB communication status and identify which axis amplifier is failing to respond. Note the axis number showing communication error.
4
Verify FSSB network topology matches parameter settings. Check parameter 8101 (FSSB axis configuration) and 8102 (FSSB spindle configuration) to confirm axis assignment matches physical wiring.

DIY Feasiblehigh confidence

Call a technician if:

·Amplifier hardware replacement required
·Multiple amplifiers showing communication errors
·FSSB auto-setup fails repeatedly

Prevention

Protect FSSB cables from mechanical damage with proper routing
Perform monthly optical connector cleaning
Monitor parameter 1815 timeout margins during preventive maintenance

Common Mistakes

Looking into optical fiber connectors
Forcing bent FSSB cables to fit
Changing FSSB parameters without understanding system configuration

Related Alarms

5135 5136 5140 401 402

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