Fanuc alarm SV0303: APC ALARM: FRAMING ERROR
servo APC alarm (absolute pulse coder) · Fanuc 0i-D
What it means
The serial data stream from the absolute position detector arrived with a framing error, so the CNC could not reconstruct a valid machine position. Framing errors mean the start/stop bit boundaries of the transmitted characters were misread, which points to a marginal signal rather than corrupt data content. The detector, its cable, or the servo interface module is the suspect hardware.
Likely causes
- Damaged or contaminated absolute pulse coder cable or connector
- Failing pulse coder internal electronics
- Noise pickup from routing signal cables alongside power cables
- Faulty servo amplifier interface circuit
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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A860-2000-T301
pulse-coder · Common cause
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A860-2070-T301
pulse-coder · Common cause
Need the part urgently?
Send us alarm SV0303 with your machine details — typical RFQ turnaround is 24–48h.