Code 230640: <location>SI MM: Fault in the shutdown path of the second channel
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>SI MM: Fault in the shutdown path of the second channel 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: All objects Reaction: OFF2 Acknowledge: IMMEDIATELY (POWER ON) Cause: The Motor Module has detected a communications error with the higher-level control or the TM54F to transfer the safety-relevant information. Note: This fault results in a STOP A that can be acknowledged. Fault value (r0949, interpret decimal): Only for internal Siemens troubleshooting. Remedy: For the higher-level contro l, the following applies: - check the PROFIsafe address in the higher-level control and Motor Modules and if required, align. - save all parameters (p0977 = 1). - carry out a POWER ON (power off/on) for all components. For TM54F, carry out the following steps: - start the copy function for the node identifier (p9700 = 1D hex). - acknowledge hardware CRC (p9701 = EC hex). - save all parameters (p0977 = 1). - carry out a POWER ON (power off/on) for all components. The following generally applies: - upgrade the Motor Module software. Note: MM: Motor Module SI: Safety Integrated See also: p9810 (SI PROFIsafe address (Motor Module))
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 230640 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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