System diagramFunction introduction Function overview:Can be applied to more than one floor of the villa, access to 4 to 1 sets of indoor extensionCan be applied to multiple entrances and exits of the villa, access to 4 to 1 units at the entrance of the machineIt calls between the transfer and internal extension call intercom functionWith night vision function, equipped with LED lighting compensationAccess control reading head (optional) Technical parameter:Operating voltage: DC18V + 10% (provided by extension, each extension shall be connected to the power supply)Working current: host: = 230mA extension: 500mAOperating temperature: host: -40 C ~ +70 C extension: -10 C ~ +50 CWiring way: 4 bus (RVV4 * 0.5)The transmission distance is less than 100 meters.Video signal: 1Vp-p/75Host c...