Code 233111: <location>Encoder 3: Absolute encoder EnDat, internal fault/error
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Encoder 3: Absolute encoder EnDat, internal fault/error 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 bin Drive object: All objects Reaction: A_INFEED: NONE SERVO: OFF1 (IASC/DCBRAKE, NONE, OFF2, OFF3) VECTOR: OFF1 (IASC/DCBRAKE, NONE, OFF2, OFF3) Acknowledge: PULSE INHIBIT Cause: The EnDat encoder fault word supplies fault bits that have been set. Fault value (r0949, interpret binary): Bit 0: Lighting system failed. Bit 1: Signal amplitude too low. Bit 2: Position value incorrect. Bit 3: Encoder power s upply overvoltage condition. Bit 4: Encoder power supply undervoltage condition. Bit 5: Encoder power s upply overcurrent condition. Bit 6: The battery must be changed. Remedy: Re fault value, bit 0 = 1: Encoder is defective. Replace the encoder, w here the motor encoder has a direct DRIVE-CLiQ socket: Replace the motor. Re fault value, bit 1 = 1: Encoder is defective. Replace the encoder, w here the motor encoder has a direct DRIVE-CLiQ socket: Replace the motor. Re fault value, bit 2 = 1: Encoder is defective. Replace the encoder, w here the motor encoder has a direct DRIVE-CLiQ socket: Replace the motor. Re fault value, bit 3 = 1: 5 V power supply voltage fault. When using an SMC: Check the plug-in cable between the encoder and SMC or replace the SMC. When a motor encoder with a direct DRIVE-CLiQ connection is used: Replace the motor. Re fault value, bit 4 = 1: 5 V power supply voltage fault. When using an SMC: Check the plug-in cable between the encoder and SMC or replace the SMC. When using a motor with DRIVE-CLiQ: Replace the motor. Re fault value, bit 5 = 1: Encoder is defective. Replace the encoder, w here the motor encoder has a direct DRIVE-CLiQ socket: Replace the motor. Re fault value, bit 6 = 1: The battery must be changed (only for encoders with battery back-up).
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 233111 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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