Before connecting the siren, you must update the time clock to the latest firmware. Then: 1) Connect the red wire from the clock to the black wire of the power supply. 2) Connect the black wire from the clock to the black wire from the siren. 3) Connect the red wire from the power supply (It could be white when using DC Adapter) to the red from the siren. 4) Press the Menu button of the time clock to go into the main menu screen. Press OK on System, then press OK on Misc Settings", then press OK on "External Bell", then press OK on "Change to External Only". 5) Then, press Menu > System > Bell > Set the Bell setting like time, Day type & Enable the bell. 6) Set the Ring Period to 3. ( 3 second) and save it. And schedule the clock bell. Menu > System Bell > Set the day and time it should ring.