Code 4050: NC code identifier %1 cannot be reconfigured to %2
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical NC code identifier %1 cannot be reconfigured to %2 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
Parameters: %1 = String: Old identifier %2 = String: New identifier Definitions: Renaming of an NC code was not possible for one of the following reasons: - The old identifier does not exist - The new identifier lies in another type range. NC codes/keywords can be reconfigured via machine data as long as the type range is not abandoned. Type 1: "real" G codes: G02, G17, G33, G64,... Type 2: named G codes: ASPLINE, BRISK, TRANS,... Type 3: settable addresses: X, Y, A1, A2, I, J, K, ALF, MEAS,... Reaction: NC not ready. Mode group not ready, also effective for single axes NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Remedy: Please inform the authorized personnel/service department. Correct MD10712 $MN_NC_USER_CODE_CONF_NAME_TAB (protection level 1). The list must be built up as follows: Even address: Identifier to be modified. Following odd address: New identifier e.g.: $MN_NC_USER_CODE_CONF_NAME_TAB [10] = "ROT" $MN_NC_USER_CODE_CONF_NAME_TAB [11] = " " clears the ROT function from the control Program Continuation: Switch control OFF - ON.
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 4050 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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