Code 201691: <location>SI Motion: Ti and To unsuitable for DP cycle
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>SI Motion: Ti and To unsuitable for DP cycle 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, VECTOR Reaction: NONE Acknowledge: NONE Cause: The configured times for PROFIBUS communication are not permitted and the DP cycle is used as the actual value acquisition cycle for the safe movement monitoring functions: Isochronous PROFIBUS: the total of Ti and To is too high for the set DP cycle. The DP cycle should be at least 1 current controller cycle greater than the sum of Ti and To. Non-isochronous PROFIBUS: the DP cycle must be at least 4 x current controller cycle. Remedy: Configure Ti and To low so that they are suitable for the DP cycle or increase the DP cycle time. Option for enabled drive-based SI monitoring (p9601/p9801 > 0): Use the actual value sampling cycle p9511/p9311 and, t herefore, set it independently of the DP cycle. See also: p9511 (SI Motion clock cycle ac tual value sensing (Control Unit))
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 201691 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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