Siemens alarm 20003: [Channel %1: ] Axis %2 measuring system error

What it means

A fault of the measuring system was detected during the referencing run, e.g. loss of increment signals while searching for the reference mark. The approach is aborted because position feedback is no longer trustworthy.

Likely causes

• encoder signal amplitude too low (dirty scale, failing LED, aging encoder)
• broken or chafed encoder cable, poor screen bonding
• loose encoder coupling allowing slip during travel
• interference from unscreened power cables routed with the measuring circuit

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• 6FX2001 series encoder

  encoder · Common cause

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• 6FX5002 series encoder signal cable

  cable · Common cause

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