O Glossary Terms - O Offline Lock A lock that is not connected to the access control system and must be updated manually. Close OHMS The measure of resistance of an electrical device to the flow of electricity. Close OHMS Law Relationship of voltage, current and resistance in a circuit, E = I x R. (where E is voltage, I is current, and R is resistance). Close Online Lock A lock that is constantly connected to the access control system (typically through an access control panel). Close Open Back Strike For use with a pair of doors. The back of the strike is cut away, permitting the inactive door to be opened independently. Close Opening Force Force required to open a door against the closers spring power. Close OSDP Open Supervised Device Protocol is the latest Access Control industry standard for hard-wired reader communications. OSDP is an RS-485, bi-directional protocol that can both support encryption and higher data speeds than its predecessor (Wiegand) as well as longer distances (4000 ft.). Close