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FANUC Controller
Servo/Axis · Intermediate · 5-30 minutes
Fanuc 495 - Fssb tandem error
Alarm 495 indicates a communication failure in a tandem FSSB configuration where two or more axes are controlled on the same servo bus channel. This occurs when the CNC detects a mismatch, synchronization error, or communication breakdown between tandem-configured amplifiers on the FSSB network.
495
Fanuc 495 - Fssb tandem error
FSSB TANDEM ERROR
An FSSB (Fanuc Serial Servo Bus) error has been detected related to fssb tandem error. The serial bus communication between the CNC and servo amplifiers is affected.
Root Cause Summary
Alarm 495 indicates a communication failure in a tandem FSSB configuration where two or more axes are controlled on the same servo bus channel. This occurs when the CNC detects a mismatch, synchronization error, or communication breakdown between tandem-configured amplifiers on the FSSB network.
Safety
- Verify corrected program or parameters before resuming machining
Causes and Fixes
- 1
Power down the machine and inspect all FSSB cables between the CNC and each tandem amplifier, checking for physical damage, bent pins, or loose connections.
Always follow LOTO procedures before opening electrical cabinets.
- 2
Verify the FSSB cable routing follows proper shielding practices and is separated from power cables by at least 100mm to prevent noise interference.
- 3
Check that termination resistors are properly installed only at the last amplifier in the FSSB chain, not at intermediate tandem units.
- 4
Replace FSSB cables one at a time starting from the tandem axis amplifiers, using only genuine Fanuc FSSB cables with proper impedance ratings.
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