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FANUC Controller
Servo/Axis · Intermediate · 5-30 minutes
Fanuc 474 - Fssb configuration error
FSSB alarm 474 indicates a configuration mismatch between the CNC control parameters and the actual servo amplifiers connected on the serial bus. This typically occurs when the parameter settings don't match the physical hardware configuration, axis assignments are incorrect, or amplifier addressing conflicts exist on the FSSB network.
474
Fanuc 474 - Fssb configuration error
FSSB CONFIGURATION ERROR
An FSSB (Fanuc Serial Servo Bus) error has been detected related to fssb configuration error. The serial bus communication between the CNC and servo amplifiers is affected.
Root Cause Summary
FSSB alarm 474 indicates a configuration mismatch between the CNC control parameters and the actual servo amplifiers connected on the serial bus. This typically occurs when the parameter settings don't match the physical hardware configuration, axis assignments are incorrect, or amplifier addressing conflicts exist on the FSSB network.
Safety
- Verify corrected program or parameters before resuming machining
Causes and Fixes
- 1
Access diagnostic screen 0 (SYSTEM) and check parameter 8100-8109 to verify the FSSB channel configuration matches your physical setup (JA1=channel 1, JA2=channel 2).
- 2
Check parameters 1020-1023 (serial number) to verify they match the amplifier models physically installed. Document current values before any changes.
Incorrect parameter changes can cause axis runaway. Always enable emergency stop before parameter modifications.
- 3
Verify parameter 8110-8139 (axis assignment to FSSB channels) matches your machine's actual axis-to-amplifier wiring configuration.
- 4
Power cycle the complete system (control and amplifiers) after parameter corrections to reinitialize FSSB communication and clear configuration cache.
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