Code 207311: <location>Bypass motor switch
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Bypass motor switch 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: Fault cause: %1 bin Drive object: SERVO, VECTOR Reaction: OFF2 Acknowledge: IMMEDIATELY SINAMICS-Alarms Cause: Fault value: Bit field BYPASS_CONTACTOR_ERROR_STATE Bit 1 BYPASS_CONTACTOR_ERR_FBK_ON_MISSING Switch "Closed" feedback signal missing Bit 2 BYPASS_CONTACTOR_ERR_FBK_OFF_MISSING Switch "opened" feedback signal missing Bit 3 BYPASS_CONTACTOR_ERR_TOO_SLOW Switch feedback signal too slow: After switching, the system waits for the posit ive feedback signal. If the f eedback signal is received later than the specified time, then a fault trip (shutdown) is issued. Bit 6 BYPASS_CONTACTOR_ERR_BYPASS_INCONSISTENCY Drive switch feedback signal is not consistent with the bypass state: When powering up or for STAGING, the drive switch is closed. See also: p1260 (Bypass configuration), r1261 (Byp ass control/status word), p1266 (Bypass, control command), p1267 (Bypass changeover source confi guration), p1269 (Bypass switch feedback signal), p1274 (Bypass switch monitoring time) Remedy: - check the transfer of the feedback signals. - check the switch
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 207311 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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