Code 207993: <location>Drive: Incorrect direction of rotation of the field or encoder actual value inversion
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Drive: Incorrect direction of rotation of the field or encoder actual value inversion 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: SERVO Reaction: OFF2 (NONE) Acknowledge: IMMEDIATELY Cause: Either the direction of the rotating field or the enc oder actual value has an incorrect sign. The motor data identification automati cally changed the actual value inversion (p0410) in order to correct the control sense. This can result in a direction of rotation change. To acknowledge this fault, the correctness of the direction of rotation must first be acknowledged with p1910 = -2. SINAMICS-Alarms Diagnostics Manual (DAsl), 03/2009 Remedy: Check the direction of rotation, also for t he position controller, if one is being used. If the direction of rotation is correct, the following applies: No additional measures are required (e xcept p1910 = -2 and acknowledge fault). If the direction of rotation is incorrect, the following applies: To change the direction of rotation, two phases must be interchanged and the motor identification routine must be repeated.
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 207993 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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