Safety functions (STO-SBC)

SOMANET Circulo provides two drive integrated safety functions according to IEC 61800-5-2:2017 as a pure hardware solution

1. STO (Safe Torque Off) prevents the creation of torque in the motor and enables an uncontrolled stop in accordance with stop category 0 of IEC 60204-1.

2. SBC (Safe Brake Control) provides a switchable (PWM) voltage output (0 V - U_bus) to directly and safely control an external motor brake.


The safety circuit safely inhibits currents to the motor and to a brake when STO-SBC command has been given (e.g. from an emergency stop device).

When the command has been released (e.g. manually resetting the emergency stop device) the currents are allowed to be carried to the motor and to the brake.

The safety system must be designed to meet the requirement “restarting the machinery after a stoppage must be possible only by an intended actuation of a control device provided for the purpose”.