Safety specifications

System requirements

Required Firmware

  • v4.2.0 or higher

Supported Hardware

  • SOMANET Circulo 7

  • SOMANET Circulo 9

Technical specifications

Safety parameters

Safety Integration level (SIL) according to IEC 61508:2010


Performance Level (PL) according to ISO 13849-1:2015

PL e

Reaction time

10 ms

Safety parameters IEC 61508:2010

Probability of dangerous failure per hour (PFH d)

1.59∙10 -10 /hour

Probability of dangerous failure on demand (PFD avg)

1.39∙10 -5

Safe Failure Fraction (SFF)


Hardware Fault Tolerance (HFT)



Type A

Mission time T M

20 a

Supported safety modes

High, Low

Safety parameters ISO 13849-1:2015


Cat. 3

Mean Time to dangerous Failure (MTTF d)

3319 years (capped to 100 years)

Diagnostic coverage (DC avg)


Common Cause Failure (CCF)


Installation requirements

Max. installation altitude

2000 m

Pollution Degree

PD 2

Supported Motors

1 × 3-phase BLDC-Motor and 1 active brake


Servo drives including STO-SBC module shall be used only in Pollution Degree environments class PD 2 according to IEC 61800-5-1:2007. During normal operation only non-conductive pollution may occur, temporarily occurring conductivity caused by condensation may only be expected when the servo drive is out of operation.

PD2 environment can be reached for example with environmentally controlled location which does not contain conductive contamination or by using IP54 enclosure according to IEC 60529:1989 + A1:1999 + A2:2013.

Safe digital inputs (STO-SBC input)

Number of digital inputs

2 (dual-channel safety input for activating STO-SBC function)

Digital input type according to IEC61131-2:2007

Type 1

Voltage range

0-60 VDC

Max. transient input voltage

80 VDC

Input voltage, logic 1

15-60 V

Input voltage, logic 0

0-5 V

Input current

Max. 6 mA (@24 VDC)

Test pulse toleration (OSSD pulses)

Max. 1 ms

Reverse voltage protected


Allowed discrepancy between digital inputs

100 ms

De-activation time

10 ms

Safe brake output (SBC)

Number of digital outputs

2 (dual-channel safety output for one brake system)

Max. output voltage

Servo drive main power supply (48 VDC)

Min. output voltage

0 V

Max. current.

1 A

Max. peak current.

4 A


This PWM controlled brake is configured by the same object as the regular brake.