Siemens alarm 300504: Axis %1 drive %2 measuring circuit error of motor measuring system
SINUMERIK 840D/810D powerline drive alarm (SIMODRIVE 611D) · SIMODRIVE 611D/611U
What it means
Signal level of the motor encoder too low or disturbed - the drive cannot trust motor feedback.
Likely causes
- encoder (EnDat/resolver) failing or damaged
- encoder cable intermittency, esp. in trailing cable tracks
- poor shielding / missing shield bond at control-module front screw
- dirty linear scale (linear motors) or bad gearwheel-sensor gap
- defective 611D closed-loop control module
Triage note: Check shield connection on top screw of control-module front plate; use original Siemens encoder cables (high shielding grade).
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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6FX5002-2E…
original Siemens preassembled encoder/signal cable · Primary suspect
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ERN1387/EQN1325 or motor-integrated encoder
motor encoder · Common cause
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6SN1118-…
SIMODRIVE 611D closed-loop control board · Common cause
Need the part urgently?
Send us alarm 300504 with your machine details — typical RFQ turnaround is 24–48h.