Protecting people and investments with drives safety: certified, built-in, more efficient, lower cost

drives safety

SINAMICS Safety Integrated

The SINAMICS family not only offers drives for each power and performance level, but also include safety functionality seamlessly integrated throughout the portfolio. Whether hardwired into an existing system or linked via PROFIsafe to SIMATIC or SINUMERIK controls utilizing failsafe communication, Sinamics drives allow you to innovate to the latest safety concepts. This offers you shorter commissioning times and higher cost effectiveness thanks to efficient engineering and certified solutions.

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drives safety - sinamics s120

Why choose SINAMICS Safety Integrated?

  • Global safety-certified products and solutions
  • Easy integration into SIMATIC automation 
    — Failsafe PLC’s
    — Drive safety library in TIA portal
  • Failsafe communication network over the same network cable with PROFIsafe
  • Full range of drive-based safety integrated features that can be flexibly applied
  • Capability to do high-level safety concepts such as safe kinematics for motion control
  • Support of lifecycle such as SET for design to Safety Acceptance Testing for commissioning and documentation
Safety functions

Integrated drives safety functions

Siemens failsafe drives are characterized by integrated safety function as possible responses to safety-related events. The available functions described below satisfy the requirements defined in Part 5-2 of the international standard IEC 61800 for variable-speed drive systems. The SBT and SP functions go beyond the scope laid down in IEC 61800-5-2.  

Functions to safely stop the drive

STO safety sets the drive into a torque-free condition: an undesirable restart is safely prevented. A fast restart is possible after STO has been deselected as the DC link remains charged

The STO function is the most common and basic drive-integrated safety function. It ensures that no torque-generating energy can continue to affect a motor and prevents unintentional start-ups. This function is a mechanism that prevents the drive from restarting unexpectedly, in accordance with EN 60204-1, Section 5.4.



 The Safe Torque Off function clears the pulses of the drive, making it reliably torque-free. This state is monitored internally in the drive.



STO has the immediate effect that the drive cannot supply any torque-generating energy. STO can be used wherever the drive will reach a standstill in a sufficiently short time based on the load or friction or when the coasting down of the drive will not have any relevance for safety.



The advantage of the integrated STO safety function compared to standard safety technology using electromechanical switchgear is the elimination of separate components and the effort that would be required to wire and service them. Because of the rapid electronic switching times, the function has a shorter switching time than the electromechanical components in a conventional solution.

Siemens drives with STO integrated safety

The drive is quickly and safely stopped and monitored – especially for high moments of inertia

The SS1 function causes a motor to stop rapidly and safely and switches the motor to torque-free mode after the standstill, i.e. STO is activated. The Safe Stop 1 function can safely stop the drive in accordance with EN 60204-1, Stop Category 1.



When the SS1 function is selected, the drive brakes along a quick stop ramp autonomously and automatically activates the Safe Torque Off and Safe Brake Control functions (if enabled) when the parameterized safety delay timer expires.



The SS1 function is used when in the event of a safety-relevant incident the drive must stop as quickly as possible with a subsequent transition into the STO state. It is thus used to bring large centrifugal masses to a stop as quickly as possible for the safety of operating personnel, or to brake motors at high speeds as quickly as possible. Typical application examples include saws, grinding machine spindles, centrifuges, stacker cranes.



The targeted stopping of a drive by means of SS1 reduces the risk of danger, increases the productivity of a machine, and allows safety clearances in a machine to be reduced. The reason is the active stopping of the drive compared to the use of the STO function alone.

Siemens drives with SS1 integrated safety

The drive is quickly and safely stopped and then SOS is activated

The SS2 function shuts down a motor quickly and safely and then monitors the standstill positions, in accordance with EN 60204-1, Stop Category 2.



When the SS2 function is selected, the drive brakes autonomously along a quickstop ramp. In contrast to SS1, the automatic speed control remains operational afterwards, i.e. the motor can supply the full torque required to maintain zero speed. Standstill is safely monitored (Safe Operating Stop function).



As with SS1, the SS2 function ensures the quickest possible deceleration of the motor. However, the motor power is not switched off, but prevented by a control system from leaving the standstill position even if affected by external forces.



The SS2 function ensures a rapid axis stop. Because the control remains active, after the safety function is deselected, productive operation can continue without referencing. This ensures short setup and standstill times and high productivity.

Siemens drives with SS2 integrated safety

The position is safely held and monitored at standstill for each drive control

With the SOS function, the stopped motor is kept in its position and monitored by a drive control.



The Safe Operating Stop function represents safe standstill monitoring. The drive control remains in operation. The motor can therefore deliver the full torque to hold the current position. The actual position is reliably monitored. In contrast to safety functions SS1 and SS2, the speed setpoint is not influenced automatically. After SOS has been activated, the higher level control must bring the drive to a standstill within a parameterized time and then hold the position setpoint.



SOS is an ideal solution for applications in which the machine or parts of the machine must be at a safe standstill in certain steps, but the drive must also supply a holding torque. It is ensured that despite counter torque the drive remains in its current position. In contrast to SS1 and SS2, the drive does not brake autarchically in this case. It expects the higher-level controller to shut down the relevant axes as a coordinated group within an adjustable delay time. This can be used to prevent any damage to the machine or product.



No mechanical components are necessary to keep the axis in position despite any counterforce that might appear. Due to the short switching times and the fact that the position control always remains active, setup and downtimes are reduced. Recalibration of the axis after exiting the SOS function is not necessary. The axis can immediately be moved again after deactivation of the SOS function.

Siemens drives with SOS integrated safety

Functions for safe brake management

A holding brake is controlled and monitored in a safety-related fashion, especially for vertical axes; is always activated in parallel with STO

The SBC function permits the safe control of a holding brake -  always activated in parallel with STO.



A holding brake which is active in a de-energized state is controlled and monitored using safe two-channel technology. Due to this level of control, the brake may still be activated in the event of an insulation fault in the control cable. Errors of this kind are detected early by means of test pulses.



The SBC function is used in conjunction with the functions STO or SS1 to prevent the movement of an axis in the torque-free state, e.g. because of gravity.



Again, the function saves the use of external hardware and the associated wiring.

Siemens drives with SBC integrated safety

Up to two brakes per axis can be cyclically tested using the SBT diagnostic function

This performs a test of the brake function at cyclical intervals.



The intended function of wear-prone brakes is safely tested by increasing torque against the closed brake. Two brakes can be tested with different test torques on each drive, e.g. motor brake and external brake.



This function is suitable for implementing a safe brake combined with the SBC function.



The function identifies faults or wear in the brake mechanics. Automatically testing the effectiveness of brakes reduces maintenance costs and increases the safety and availability of plants / machines. Goes beyond the safety functions named in IEC 61800-5-2d.

Siemens drives with SBT integrated safety

Functions for safely monitoring drive motion

The speed/velocity value of the drive is monitored in safety-related fashion, and a configurable stop response is initiated when the limit value is violated

The SLS function ensures that the drive does not exceed a preset speed limit.



The drive reliably monitors the speed and activates a fault response defined by the configuration if the set speed / rpm limit is exceeded.



The SLS function is used if people are in the danger zone of a machine and their safety can only be guaranteed by reduced speed. First, therefore, the speed is reduced, then safe monitoring is activated using the SLS function so that accidental exceeding of the set speed limit is prevented. Typical examples are cases in which an operator must enter the danger zone of the machine for maintenance or setup. A typical use of SLS is a winder, in which the material is manually threaded by the operator. To prevent injury to the operator, the roller may only spin at a safe reduced speed. SLS is often also used as part of a two-stage safety concept. While a person is in a less critical zone, the SLS function is activated, and the drives are only stopped in a smaller area with higher potential risk. SLS can be used not only for operator protection, but also for machinery protection, e.g. if a maximum speed must not be exceeded.



The SLS function can contribute to a significant reduction in downtime, or greatly simplify or even accelerate setup. The overall effect achieved is a higher availability of a facility. Moreover, external components such as speed monitors can be omitted.

Siemens drives with SLS integrated safety

A safety-related velocity/speed monitoring function supplies a safety-rated signal as long as the drive operates below a specified speed/feed velocity

The SSM function warns when a drive is working below a specified speed / feed speed. As long as it remains below the threshold, the function issues a safety signal.



If a speed value drops below a parameterized level, a safety signal is generated. This can be processed, for example, in a safety controller to respond to the event by programming, depending on the situation.



With the SSM function, in the simplest case, a safety door can be unlocked if the speed drops below a non-critical level.



Unlike SLS, there is no drive-independent fault reaction when the speed limit is exceeded.

The safe feedback can be evaluated in a safety control unit, allowing the user to respond appropriately to the situation.

Siemens drives with SSM integrated safety

The direction of rotation is monitored in a safety-related fashion so that the drive can only move in the permissible direction; a configurable fault response is initiated if the drive moves in the incorrect direction

The SDI function ensures that the drive can only rotate in the selected direction.



A deviation from the currently monitored direction of motion / rotation is reliably detected and the configured autonomous fault response of the drive is initiated. It is possible to monitor both directions of motion optionally.



The SDI function is used if the drive must only move in one direction. A typical application is to make a danger zone accessible to the operator, provided the machine is moving in the safe direction, i.e. away from the operator. In this status, the operator can safely feed material into or remove it from the work area.



The function does away with the use of external components such as speed monitors and the associated wiring expense. The release of a danger zone while the machine is moving away from the operator also raises productivity. Without the SDI function, the machine would have to be stopped safely while material was fed in or removed.

Siemens drives with SDI integrated safety

It is safely monitored that the drive does not exceed a preset acceleration limit value

The acceleration of the drive can be safely limited with the SLA function



When the SLA function is activated, it monitors the relevant parameters to prevent the acceleration of the drive from exceeding the configured limit. If a limit is exceeded, a configurable error response is initiated. Acceleration is monitored in both directions of motion. Negative acceleration, i.e. braking of the drive, is not monitored. SLA is immediately active when selected. There is no delay time between the selection and the activation of the function. SLA can only be used in a single-encoder system. SLA selection is only possible via PROFIsafe.



SLA can be used, for example, in the setup mode of a machine. A bad "pass" of a drive is detected very quickly by SLA and the appropriate error response can be initiated immediately. An operator of the machine in the vicinity is thus effectively protected



The fast reaction to a dangerous operating state of the drive enables smaller protective distances and thus saves space and costs.

Siemens drives with SLA integrated safety

The SLT function is used to protect against undesired high torque or force of a drive in both directions of rotation


SLT is achieved by two-channel monitoring of the current motor torque for a torque limit. Safely Limited Torque prevents the configured limit from being exceeded. The limits must be specified based on results of the risk analysis.


Up to four different SLT limit values can be set with parameter p9532, and it is possible to dynamically switch between these limit values even when SLT is active. The PDC drive controller complies with the definition of the SLT function in IEC 61800-5-2: "This function prevents the motor from exceeding the specified torque (or, when using a linear motor, the specified force)."



The SLT safety function may be used with single- and three-phase motors (DC and EC motors). There are no special requirements on the used encoder system of the motor for the use of the SLT safety function.



The SLT function allows the operation of an electrically driven machine component at temporarily reduced safe torque or force.

Siemens drives with SLT integrated safety

Functions for safely monitoring the position of a drive

Protection zones are monitored in a safety-related fashion using defined traversing ranges

This function monitors the axis to ensure that it remains within the permissible traversing range.



The traversing range limited by the configured software limit switch is safely monitored. If the permitted traversing range is exited, a configurable fault response is initiated. It is possible to toggle between two traversing ranges, even during operation.



SLP is used for applications in which machine operators have to enter a protection area, e.g. for feeding in and removing material. Safe monitoring of the axis position ensures that the axis cannot move into the protection area released for operators, placing them in danger, e.g. for stacker cranes, gantry cranes, production centers.



SLP can be used for highly-effective protection area monitoring, eliminating the use of external components such as hardware limit switches and the associated wiring complexity. Because the response time following a limit overshoot is short, safety clearances can be reduced.

Siemens drives with SLP integrated safety

The SP function transfers the safe position actual values of the drive to the F control for further processing via PROFIsafe

Transfers the safely determined actual position values in the drive to a safety controller via safe PROFIsafe communication.



Unlike the SLP function, which monitors the current actual position value against a limit within the drive and initiates an autonomous fault response by the drive to an overshoot, SP communicates the current actual position values to the safety control. This allows Monitoring functions to be implemented more flexibly.



Tailored safety concepts can be developed with the SP function. The function is particularly suitable for machines where flexible safety functions are required. It can be used in a wide range of applications, e.g. to implement safe, axis-specific range recognition via safe cams (SCA). The function can also be used to design cross-axis safety concepts, multi dimensional protection areas and zone concepts.



Additional sensors or external safe encoders, their installation and evaluation are not necessary to monitor protection areas. The function goes beyond the safety functions stated in IEC 61800-5-2.

Siemens drives with SP integrated safety

Safe cams supply a safety-related signal if the drive is located within a configured position range

Supplies a safety-related signal as long as the drive operates within a specified position range



Can be used with a high degree of versatility for safety-related, axis-specific range identification or working area/protective area demarcation.



Used to implement safe electronic cam sequencers without requiring any hardware cams.

Siemens drives with SCA integrated safety

Overview of safety integrated – SINAMICS drives family

You can find detailed descriptions and application examples for the safety functions here

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Application examples

Comparing conventional to integrated safety

SINAMICS drives simplify your work – from standalone solutions to safety functions fully integrated in the automation environment. You can create your safety concept without complex wiring – instead, safety functions are simply activated. The guided acceptance test, as well as the comprehensive documentation, provide you with user-friendly support when documenting and validating your machine's safety. When compared to conventional safety technology, using SINAMICS Safety Integrated can save both time and expense.

Siemens customers are convinced

Significant advantages are obtained for both machine OEMs and users by safety functions integrated in the drive. The costs to realize a safe machine are drastically reduced – and the reliability of the solution has been clearly proven in many applications around the globe.

Together safe with Safety Integrated in the TIA Portal

Tutorial for configuring and commissioning SINAMICS G120C and SIMATIC S7-1200F in TIA Portal.

Additional information

Failsafe drive technology

The Safety Evaluation Tool provides you with swift and reliable help in assessing the safety functions of your machine. The TÜV-tested online tool for standards IEC 62061 and ISO 13849-1 gets you straight to your goal [TÜV = German technical inspectorate]. As a result you receive a standards-compliant report that can be integrated in the documentation of your system or machine as proof of safety.

Keep on the safe side using the free-of-charge Safety Evaluation Tool

Safety Evaluation Tool