Fagor alarm 2052: Too much real feedback difference.
CNC 8055 hardware/feedback error (analog axes) · Fagor 8055/8055i
What it means
On axes using dual feedback (motor encoder as first feedback plus a linear scale as second feedback), the CNC compares both positions continuously. The alarm fires when the difference exceeds a.m.p. FBACKDIF (P100), or - with the feedback-combination feature active - when the two count directions disagree or the divergence exceeds 838 mm. It indicates one feedback is slipping, losing counts, or scaled wrong.
Likely causes
- linear scale reading wrong (contamination, damaged glass, loose read head)
- motor encoder coupling slipping on the ball screw side
- count direction of first and second feedback opposite (sign/pin swap)
- FBACKDIF threshold unrealistic for the machine's lost motion
- scale cable intermittently dropping counts
Triage note: Jog the axis slowly and watch both positions on the diagnosis screen: whichever feedback stays behind identifies the failing device. Setting FBACKDIF = 0 disables the check but masks a real fault.
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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SX-520 / SX-525 linear scale (second feedback)
scale · Common cause
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Scale/read-head feedback cable
cable · Common cause
Need the part urgently?
Send us alarm 2052 with your machine details — typical RFQ turnaround is 24–48h.