[i need help pleas]

hello
i need help in my graduation project
my project is to make scada system to asmall factory
i have to control and monitor some parameter of the factory
such like tempreture, lighting, fire and voltage and i have to make allarming system
i have to monitor them on the pc and to control them through master computer
i have to use pic or plc
and serial communication between the sensors and th master computer
please help me
thanx