Design of a multi-spots temperature monitoring and alarming system based a person computer

In this paper a multi-spots temperature monitoring and alarming system based on a person computer is designed. The system consists of a person computer as a host and a subsystem as a slave. The host can communicate with the slave by its serial port. The host can also control the slave and receive temperature value from it that can be displayed on the screen of the host. The host will alarm when the temperature value is beyond the user-defined two´s complement alarm trigger values. The user program of the host is developed by Visual c++ 6.0. The slave consists of a microcontroller unit AT89S52, temperature sensors DS18B20, serial port electrical level converting circuit, alarm circuit, display circuit, power circuit and so on. The slave can receive temperature data from the sensors that can be displayed on its display and be sent to the host. The slave will also alarm when the temperature value is beyond the user-defined two´s complement alarm trigger values. The system is simple, its cost is low and its operation is easy. Its accuracy and resolution is excellent.