Code 207551: <location>Drive encoder: No commutation angle information
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Drive encoder: No commutation angle information alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Message value: Fault cause: %1, drive data set: %2 Drive object: SERVO, VECTOR Reaction: OFF2 (IASC/DCBRAKE) Acknowledge: IMMEDIATELY (POWER ON) Cause: The commutation angle information is missing. Th is means that synchronous motors cannot be controlled (closed-loop control) Fault value (r0949, interpret decimal): yyyyxxxx dec: yyyy = fault cause, xxxx = drive data set yyyy = 1 dec: The motor encoder used does not s upply an absolute commutation angle. yyyy = 2 dec: The selected ratio of the measuring gear does not match the motor pole pair number. SINAMICS-Alarms Remedy: Re fault cause = 1: - check the encoder parameterization (p0404). - use an encoder with track C/D, EnDat interface of Hall sensors. - use an encoder with sine-wave A/B track for which the motor pole pair number (r0313) is an integer multiple of the encoder pulse number (p0408). - activate the pole position identification routine (p1982 = 1). Re fault cause = 2: - the quotient of the pole pair number divided by the ratio of the measuring gear must be an integer number: (p0314 * p0433) / p0432. Note: For operation with track C/D, this quotient must be less than 8. See also: p0402, p0404, p0432, p0433
Source: SINUMERIK 840D sl / 840Di sl / SINAMICS S120 Diagnostics Manual (DAsl, 03/2009)
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Siemens SINUMERIK 840D CNC Alarms
Siemens controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code 207551 on the SINUMERIK 840D CNC identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Siemens's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 4014 Siemens SINUMERIK 840D CNC codes.
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