Code 207982: <location>Drive: Rotating measurement encoder test
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Drive: Rotating measurement encoder test 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: VECTOR Reaction: OFF1 (NONE, OFF2) Acknowledge: IMMEDIATELY Cause: A fault has occurred during the encoder test. Fault value (r0949, interpret decimal): 1: The speed did not reach a steady-state condition. 2: The speed setpoint was not able to be approached as the minimum limiting is active. 3: The speed setpoint was not able to be approached as the suppression (skip) bandwidth is active. 4: The speed setpoint was not able to be appr oached as the maximum limiting is active. 5: The encoder does not supply a signal. 6: Incorrect polarity. 7: Incorrect pulse number. 8: Noise in the encoder signal or speed controller unstable. 9: Voltage Sensing Module (VSM) incorrectly connected. SINAMICS-Alarms Remedy: Re fault value = 1: - check the motor parameters. - carry out a motor data identification routine (p1910). - if required, reduce the dynamic factor (p1967 < 25 %). Re fault value = 2: - adapt the speed setpoint (p1965) or adapt the minimum limit (p1080). Re fault value = 3: - adapt the speed setpoint (p1965) or suppre ssion (skip) bandwidths (p1091... p1094, p1101). Re fault value = 4: - adapt the speed setpoint (p1965) or maximum limit (p1082, p1083 and p1086). Re fault value = 5: - check the encoder connection. If required, replace the encoder. Re fault value = 6: - check the connection assignment of the enc oder cable. Adapt the polarity (p0410). Re fault value = 7: - adapt the pulse number (p0408). Re fault value = 8: - check the encoder connection and encoder cable. It is possible that there is a problem associated with the ground connection. - reduce the dynamic response of the s peed controller (p1460, p1462 and p1470, p1472). Re fault value = 9: - check the connections of the Voltage Sensing Module (VSM). Note: The encoder test can be switc hed out (disabled) using p1959.0. See also: p1959
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 207982 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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