Code 12300: [Channel %1: ] Block %2 call-by-reference parameter missing on subroutine call %3
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical [Channel %1: ] Block %2 call-by-reference parameter missing on subroutine call %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 = Source string Definitions: In the subroutine definition, a formal REF parameter (call-by-reference parame ter) has been specified with no actual parameter assigned to it. The assignment takes place in the subroutine call on the basis of the position of the variable name and not on the basis of the name! Diagnostics Manual (DAsl), 03/2009 Example: Subroutine: (2 call-by-value parameters X and Y, 1 call-by-reference parameter Z) PROC XYZ (INT X, INT Y, VAR INT Z): M17 ENDPROC Main program: N10 DEF INT X N11 DEF INT Y N11 DEF INT Z: N50 XYZ (X, Y); REF parameter Z missing or N50 XYZ (X, Z); REF parameter Z missing! 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. Assign a variable to all REF parameters (call-by-r eference parameters) of the subroutine when calling. No variable must be assigned to "normal" formal parameters (call-by-value parameters), as these are defaulted with 0. 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 12300 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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