Code 12555: [Channel %1: ] Block %2 function not available (identification %3)
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 function not available (identification %3) 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 = Fine ID Definitions: The identifier has not been defined for this system. Reaction: Correction block is reorganized. Interface signals are set. Alarm display. Diagnostics Manual (DAsl), 03/2009 Remedy: Press the NC stop key and select the "Compensati on block" function by pressing the "Program correct" softkey. The correction indicator will position in the incorrect block. - Correct the name used (write error) - Use a better software system in case of malfunction - Check the definition of variables, subroutines and macros - Declare a subroutine with EXTERNAL; load the subroutine to SPF-Dir - Check the interface definition of the subroutine 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 12555 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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