Code 12162: [Channel %1: ] Block %2 Physical unit not allowed
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 Physical unit not allowed 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 Definitions: In a DEF or REDEF instruction a physical unit may only be defined for variables of type INT or REAL. Reaction: Correction block is reorganized. Interface signals are set. Alarm display. Remedy: If the alarm occurs in the part program (DEF instruction), press the NC Stop key and select the function "Compensation block" using PR OGRAM CORRECT softkey. The cursor is placed on the incorrect block. In the compensation block the data type can now be adjusted in the DEF instruction, or the physical unit (PHU xy) must be removed. If the alarm occurs on compiling a GUD or ACCESS file, correct the GUD or ACCESS definition file (DEF file). 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 12162 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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