Code 12490: [Channel %1: ] Block %2 access permission level %3 is not valid
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 access permission level %3 is not valid 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 = Channel number %2 = Block number, label %3 = Source string Diagnostics Manual (DAsl), 03/2009 Definitions: The desired access authorization, programmed wi th the keyword REDEF, has not been set. The desired protection level is either beyond the permitt ed value range or the protection level change is not allowed. (The REDEF instruction is only executable in IN ITIAL_INI blocks on SINUMERIK 840D, P1 (6/94)). The protection level may be changed only if: 1. The current protection level is equal to or higher than the level originally defined, and 2. The new protection level is to be below the level originally defined. The higher numerical values represent the lower prot ection levels. The lower 4 levels (from 7 to 4) correspond to the keyswitch positions, and the upper 4 levels are associated with 4 passwords. Reaction: Correction block is reorganized. Interface signals are set. Alarm display. Remedy: Press the NC Stop key and select the function "C orrection block" with the softkey PROGRAM CORRECT. The correction pointer positions on the incorrect block. - Use the REDEF instruction onl y in the INITIAL_INI block - Using the operator panel, set the current protection le vel to at least the same level as that of the variable with the highest level - Program protection level within the permissible value range - Only program new protection levels that are lower than the old values Program Continuation: Clear alarm with NC ST ART or RESET key and continue the program.
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 12490 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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