Code 16949: Correspondence between marker of channel %1 and channel %2 is invalid.
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical Correspondence between marker of channel %1 and channel %2 is invalid. 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 ID %2 = Channel ID Definitions: This channel defines a WAIT marker with other channels, which on their part have no correspondence with this wait marker. This channel's WAIT marker has no explicit counterpart in the other channel; i.e. the channels do not mutually wait. ============================================================ Example Ch 3Ch 5Ch 7 WAITM(99,3,5) WAITM(99,3,5) WAITM(99,5,7) The wait markers in channels 3 and 5 mutually wait for each other and channel 7 only waits for channel 5. Therefore, channel 7 may continue when 5 and 7 have reached the wait marker, but channel 3 is still far in front of the wait marker. When it continues, channel 7 deletes its wait marker. When wait marker 99 is reached again, you can no longer determine the behavior precisely. ============================================================ Reaction: Alarm display. Remedy: In each wait marker, list all channels with which y ou want to synchronize, or suppress the alarm with MD11410 $MN_SUPPRESS_ALARM_MASK, bit 23. ============================================================ Sample solution A: Ch 3Ch 5Ch 7 WAITM(99,3,5,7) WAITM(99,3,5,7) WAITM(99,3,5,7) ============================================================ Sample solution B: Ch 3Ch 5Ch 7 WAITM(99,3,5) WAITM(99,3,5) WAITM(88,5,7) WAITM(88,5,7) ============================================================ Sample solution C: Ch 3Ch 5Ch 7 WAITM(88,5,7) WAITM(88,5,7) WAITM(99,3,5) WAITM(99,3,5) Program Continuation: Clear alarm with the Delete key or NC START.
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 16949 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.
Have a better solution?
Help the industrial community by sharing your repair experience for code 16949.
Need a searchable reference for more Siemens SINUMERIK 840D CNC manuals?
We structure equipment manuals into searchable code, title, cause, solution, safety note, and source-reference data. Send a PDF and example searched codes when you need public pages, private search, or structured exports.
Space reserved for Google AdSense / Industrial Affiliate Links
Monetization target for 2026