Perle Systems Perle IOLAN DS1 - Manual (Page 205)

I/O Wiring Diagrams 205
Wiring I/O Diagrams
Normally Closed Contact
To connect relay channel R1 for a circuit that is normally active, connect one wire to the COM
(common) connector and one wire to the NC (normally closed) connector.
COM NC NO NO COM NC
R2 R1