OSSD

What does OSSD mean?

OSSD is short for "Output signal switching device". It is part of a contactless safety system. If a signal of a contactless sensor is triggered (e.g. a light barrier) the OSSD switches off the electric circuit. Furthermore the OSSD has a functionality which allows a sensor to check itself. The installation of an OSSD is complicated since an error in the control circuit could be caused. Therefore the use of the output signal switching device has to be planned and installed with utmost accuracy.

What is an OSSD Signal?

The OSSD signal is a protective function for devices, machines and plants. If a specific sensor sends a signal the OSSD signal cuts the power and stops the plant. A typical example would be a person getting into the working space of a stocking robot. As soon as one of the light barriers or ultra sound sensors is triggered the robot is immediately stopped to prevent the person to get hurt or injured.

Additionally an OSSD signal may be used as a test signal which checks the sensor. The OSSD signal is not an actively transmitted impulse rather the output signal switching device switches the power to the sensor briefly off and checks whether the interruption was registered. If the sensor ignored this test an error is likely. Afterwards the control unit is informed about the faulty sensor and initiates further measures.

What are OSSD inputs?

An OSSD input is the connection between sensor and OSSD. In addition the OSSD input provides the required quiescent current. Via the OSSD input the action triggering signal of the sensor is transmitted.

What are OSSD outputs?

The OSSD output is the connection to the control unit. The "off" trigger is transmitted via the OSSD output to the central control unit. This tells the operating personnel where the disturbance can be found.