Code 201663: <location>SI CU: Copying of SI parameters rejected
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>SI CU: Copying of SI parameters rejected 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: Drive object: SERVO, VECTOR Reaction: OFF2 Acknowledge: IMMEDIATELY (POWER ON) Cause: One of the following values is stored in p9700 or has been entered offline: 87 or 208. This is the reason that the system is attempting to copy the SI parameters from the Control Unit to the Motor Module during booting. However, no safety function is selected on the Control Unit (p9501 = 0, p9601 = 0) which is why the copy operation is rejected. Note: This fault does not result in a safety stop response. See also: p9700 (SI Motion copy function) Remedy: - set p9700 = 0. - check p9501and p9601 and correct if necessary. - start the copy function again by entering the appropriate value in p9700.
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 201663 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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