Code 201652: <location>SI CU: Illegal monitoring clock cycle
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>SI CU: Illegal monitoring clock 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: %1 Drive object: SERVO, VECTOR Reaction: OFF2 Acknowledge: IMMEDIATELY (POWER ON) Cause: One of the Safety Integrated moni toring clock cycles is not permissible: - the drive-based monitoring clock cycle cannot be maintained due to the communication conditions required in the system. - the monitoring clock cycle for safe motion monitori ng functions with the high er-level control is not permissible (p9500). - The sampling time for the current controller (p0112, p0115) cannot be supported. Note: This fault results in a STOP A that cannot be acknowledged. Fault value (r0949, interpret decimal): - for enabled drive-based SI monitoring (p9601/p9801 > 0): Minimum setting for the monitoring clock cycle (in µs). - with the motion monitori ng function enabled (p9501 > 0): 100: No matching monitoring clock cycle was able to be found. 101: The monitoring clock cycle is not an integer mu ltiple of the actual value sensing clock cycle. 102: An error has occurred when transferring t he DP clock cycle to the Motor Module (MM). 103: An error has occurred when transferring t he DP clock cycle to the Sensor Module. 104,105: - four times the sampling time of the current contro ller is greater than 1 ms when operating with a nonclock-cycle synchr onous PROFIBUS. - Four times the sampling time of the current contro ller is greater than the DP clock cycle when operating with a clock-cycle synchronous PROFIBUS. - the DP clock cycle is not an integer multiple of the sampling time of the current controller. 106: The monitoring clock cycle does not matc h the monitoring clock cycle of the TM54F. 107: Four times the sampling time of the current co ntroller is greater than the actual value sensing clock cycle (p9511) or the actual value sensing cl ock cycle is not an integer multiple of the sampling time of the current controller. 108: The parameterized actual value sensing clock cycle cannot be set on this component SINAMICS-Alarms Remedy: For enabled drive-based SI monitoring (p9601/p9801 > 0): - upgrade the Control Unit software. For enabled motion monitoring function (p9501 > 0): - correct the monitoring clock cycle (p9500) and carry out POWER ON. Re fault value 101: - the actual value sensing clock cy cle is per default the position cont rol clock cycle / DP clock cycle. - for the drive-based motion monitoring functions (p9601/p9801bit 2 = 1) the actual value sensing clock cycle c an be directly parameterized in p9511/p9311. Re fault value = 104, 105: - set a separate actual val ue sensing clock cycle in p9511. - restrict operation to a maximum of two vector drives. For the standard settings in p0112, p0115, the current controller sampling time is automaticall y reduced to 250 µs. If the standard values were changed, then the current controller sampling time (p0112, p0115) should be appropriately set. - increase the DP clock cycle for operation with a clock-cycle synchr onous PROFIBUS so that there is a multiple clock cycle ratio of at least 4:1 betw een the DP clock cycle and the current controller sampling time. Re fault value 106: - set the parameters for the monitoring clock cycles the same (p10000 and p9500 / p9300). Re fault value 107: - set an actual value sensing cl ock cycle in p9511 that matches the current control clock cycle. Re fault value 108: - set a suitable actual value sensing clock cycle in p9511. - if, when operating with clock-cycle synchronous PR OFIBUS, the DP clock cy cle is used as actual value sensing clock cycle (p9511 = 0) a suit able DP clock cycle must be configured. A suitable multiple of the DP clock cycle (e.g. 1,2,3,4,5,6,8,10) must be parameterized on the D410. Otherwise, the clock cycle must be set to less than 8 ms. Note: CU: Control Unit MM: Motor Module SI: Safety Integrated
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 201652 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.
Have a better solution?
Help the industrial community by sharing your repair experience for code 201652.
Need a searchable reference for more Siemens SINUMERIK 840D CNC manuals?
We structure equipment manuals into searchable code, title, cause, solution, safety note, and source-reference data. Send a PDF and example searched codes when you need public pages, private search, or structured exports.
Space reserved for Google AdSense / Industrial Affiliate Links
Monetization target for 2026