Code 201630: <location>SI CU: Brake control error
Issue Description & Safety Warning
The Siemens SINUMERIK 840D CNC has triggered a critical <location>SI CU: Brake control error 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: The drive-based "Safety Integrated" function in the Control Unit (CU) has detected a brake control error and initiated a STOP A. Fault value (r0949, interpret decimal): 10, 11: Fault in "open holding brake" operation. - Parameter p1278 incorrectly set. - No brake connected or wire breakage (c heck whether brake releases for p1278 = 1 and p9602/p9802 = 0 (SBC deactivated)). - Ground fault in brake cable. 20: Fault in "brake open" state. - Short-circuit in brake winding. 30, 31: Fault in "close holding brake" operation. - No brake connected or wire breakage (c heck whether brake releases for p1278 = 1 and p9602/p9802 = 0 (SBC deactivated)). - Short-circuit in brake winding. 40: Fault in "brake closed" state. 50: Fault in the brake control circuit of the Control Un it or communication fault between the Control Unit and Motor Module (brake control). Note: The following causes may apply to fault values: - motor cable is not shielded correctly. - defect in control circuit of the Motor Module. SINAMICS-Alarms Diagnostics Manual (DAsl), 03/2009 Remedy: - check parameter p1278 (for SBC, only p1278 = 0 is permissible). - select Safe Torque Off and de-select again. - check the motor holding brake connection. - check the function of the motor holding brake. - check whether there is a DRIVE-CLiQ communication error between the Control Unit and the Motor Module involved and, if required, carry out a diagnostics routine for the faults identified. - check that the electrical cabinet design and cabl e routing are in compliance with EMC regulations (e.g. shield of the motor cable and brake conduct ors are connected with t he shield connecting plate and the motor connectors are tightly screwed to the housing). - replace the Motor Module involved. Operation with Safe Brake Module: - check the Safe Brake Modules connection. - replace the Safe Brake Module. Note: CU: Control Unit SBC: Safe Brake Control 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 201630 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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