Code 235231: <location>TM: Master control by PLC missing
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>TM: Master control by PLC missing 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: Drive object: TM41 Reaction: NONE Acknowledge: NONE SINAMICS-Alarms Cause: The "master control by PLC" si gnal was missing in operation. - interconnection of the binector input for "mas ter control by PLC" is incorrect (p0854). - the higher-level control has withdraw n the "master control by PLC" signal. - data transfer via the fieldbus (master/drive) was interrupted. Note: This alarm is only decisive in the "SIMOTION" operating mode (p4400 = 0). In the "SINAMICS" operating mode, the setpoint s at P4420 are evaluated independent of binector input p0854. Remedy: - check the interconnection of the binector i nput for "master control by PLC" (p0854). - check the "master control by PLC" signal and, if required, switch in. - check the data transfer via the fieldbus (master/drive). - check the setting of parameter p2037.
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 235231 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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