It seems you have it badly configured. For example, in the PC1832-based system, which has different ways of programming each alarm zone. If in section 001 you set the zone to 11, it means that you will have it under 24-hour surveillance, so you do not need to activate the system for the alarm to work. If you set it to 03, the alarm goes off immediately when you open the door, but you do have to have the system "armed" On the other hand, if you turn off the siren alone, you have that time incorrectly set. In this system that I told you, PC1864, in section 005, you can program how long the alarm will go off. In my case I chose 010, which means 10 minutes.