Microcomputer-Based Distributed Control and Monitoring System for Environmental Control

ABSTRACT Amicrocomputer-based distributed control and monitoring system was designed, installed and tested on four filtered-air, positive-pressure (FAPP) poultry units. The low-cost system, which provided excellent control of temperature (-h/ —1°C), humidity (less than 70%), static pressure (3.8 to 7.6 mm) and air flow could be easily adapted for other types of poultry houses, greenhouses, and heating, ventilation and air conditioning (HVAC) applications. Other features of the system which proved very useful included alarm annunciation when critical parameters were out of range, on-line data processing, automatic backup with conventional controls, a noise resistant communications link (RS-422/485), transient protection and ease with which the system could be expanded or serviced..