Abstract
The freeze drier has been used in many factory。For example pharmacy respect，preserve freshness。The pharmacy respect is used very early. When " green food " springs up, preserve freshness. The food is preserve freshness to arouse widely to value. However，Being living to transport to be a middleman .Traditional freeze-dry engine revealed more and more problems。Such as too many tip, therefore the block has made out frequently。The maintenance is not convenient. It effect the regular work of freeze-dry engine。It cut down the produce quality。
Revolving round a series of problems, people research much means, and PLC attract the foresight of crowd with such advantageous performance
A control system for a freeze drier based on PC and PLC is introduced, emphasizing on the design and implementation of the computer monitoring and control software. The techniques of multithreading and a self-made module of communication class were adopted in the program, the feasibility of the system was proved in its applications.
Key words: freeze drier; multithreading; communication; monitoring and control system
