Code 201033: <location>Units changeover: Reference parameter value invalid
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>Units changeover: Reference parameter value invalid 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: Parameter: %1 Drive object: A_INF, B_INF, S_INF, SERVO, TM41, VECTOR Reaction: NONE Acknowledge: IMMEDIATELY Cause: When changing over the units to the referred representat ion type, it is not permissible for any of the required reference parameters to be equal to 0.0 Fault value (r0949, parameter): Reference parameter whose value is 0.0. See also: p0349 (System of units, motor equivalent ci rcuit diagram data), p0505 (Selecting the system of units), p0595 (Selecti ng technological units) Remedy: Set the value of the reference parameter to a number different than 0.0. See also: p0304, p0305, p0310, p0596, p2000, p2001, p2002, p2003, r2004
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 201033 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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