Code 250001: <location>COMM BOARD: Alarm 1
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>COMM BOARD: Alarm 1 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
Message value: %1 Drive object: A_INF, B_INF, CU_LINK, CU_S, HUB, S_INF, SERVO, TB30, TM15, TM15DI_DO, TM17, TM31, TM41, TM54F_MA, TM54F_SL, VECTOR Reaction: NONE Acknowledge: NONE SINAMICS-Alarms Diagnostics Manual (DAsl), 03/2009 Cause: CBE20: A PROFINET controller attempts to establis h a connection using an incorrect configuring telegram. The PROFINET version (V2.1/V2.2) of the project (HW Config) is not compatible with the CBE20 firmware. Remedy: CBE20: Upgrade the PROFINET version of the project (HW Config) and/or the CBE20 firmware to make them compatible. See also: p8835 (CBE20 firmware selection) Drives alarms Definitions: For PROFIdrive only: A problem occured during the non-cyclic communicati on with the logical start address. The additional information defines the location of the problem. If the logical start address 0 is output, only the additional information is relevant. Reaction: Alarm display. Warning display. Remedy: Please inform the authorized personnel/service department. The alarm can be suppressed with MD11411 $MN_ENABLE_ALARM_MASK bit 1 == 0 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 250001 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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