Pilz PNOZsigma PNOZ s7 C Expansion Module Safety Relay, 24V dc, Dual-Channel, 4 Safety Contacts

"Safety features The safety relay meets the following safety requirements The circuit is internally redundant with built-in self-monitoring. The safety device remains effective in the case of a component failure. The correct opening and closing of the safety device relays is tested automatically in each on-off cycle. "