The SD500-SDM is an addressable zone module that allows IntelliKnight fire alarm controls to interface and monitor two-wire conventional smoke detectors. The SD500-SDM allows you to assign an address to a loop of conventional detection devices. These devices can be dry contacts such as pull stations and heat detectors, or 2-wire smoke detectors. This means you can retrofit an existing building and utilize existing conventional devices. The SD500- SDM uses a 24VDC auxiliary power input to power the conventional loop, and is connected to the SLC loop via two wires. The conventional loop can be configured as Class A or Class B giving you the flexibility to handle any job.