ABB's "AC500-S" safety PLC enables the control of multiple drives and improved safety performance with the optional FSO-12 safety function module. The encoderless plug-in module offers safety up to SIL3 and PLe and has safety functions such as "Safely Limited Speed" (SLS), "Safe Stop 1" (SS1) and "Safe Brake Control" (SBC). For safety functions such as "Safe direction of rotation" (SDI), which require incremental encoder feedback from the motor, the safety function module can be combined with the incremental encoder interface module 'FSE-31'. Seamless integration into the control unit of the frequency inverter is possible. The safety function module is based on the concept of integrated safety, which is already part of the 'ACS880' series and includes "Safe Torque Off" (STO) as a standard function. STO is integrated as an electronic safety function and is used instead of traditional electromechanical methods such as contactors.