The SCM-4 module uses one (1) address on an SLC loop. The module is used to supervise a Class B circuit of normally open, dry contact input devices. The SCM-4 module includes one red LED to indicate the modules status. In normal condition, the LED flashes when the device is being polled by the control panel. When a device is activated, the LED will light continuously. In case of an open circuit, the LED will turn off.