2981745 - 

Multi-application Modular System - PSR-SPP Series
This can be quickly and reliably assembled to form a tailor-made safety solution. To connect using TBUS correctly you will need one PSR-TBUS per module. For the last additional module use one PSR-TBUS-TP instead, this will close the feedback loop. The interface module is used for the connection of up to four safety sensors with NC/NO contacts to the safety relay PSR-SDC4, with screw connection.