【正文】 ing to our industry standards, BAS can be divided into equipment operation management and monitoring subsystem and fire prevention and safety subsystems, as shown. In general, these two subsystems together into BAS consider should, if the fire and safety precautions Ziji Tong independent setting, control center should be established munication with the BAS contact Yipian disaster Fasheng, can achieve the agreed operating Quan Zhuan Yi An Zhao, Jin Xing Yi Tihua coordination and contro.Building automation system39。s basic functions can be summarized as follows: (1) automatic monitoring and control of various electrical and mechanical equipment, the stop, display or print the current operating state. (2) automatic detection, display, print a variety of electrical and mechanical equipment operating parameters and changes in trends or historical data. (3) According to external conditions, environmental factors, the change automatically adjust the load of equipment, so that is always running in top condition. (4) monitoring and timely processing of all accident emergencies (5) to achieve a variety of electrical and mechanical equipment on building a unified management, coordination and control. (6) Energy management: water, electricity, gas metering and charging, etc., to achieve energy management automation. (7) Equipment Management: including device files, equipment operation and equipment maintenance management reports. The principle of building automation control systemBuilding control system used is based on modern control theory, distributed puter control system, also known as distributed control system (Distributedcontrol systems referred to as DCS). It is characterized by a centralized management decentralized control, that is charged with distribution of equipment in the field office of the microputer control (DDC) to plete device charged with the task of realtime detection and control, centralized control of puter to overe the risks of high lack of centralized control and conventional single instrument in the central control room of the central management puter with CRT display, print output, extensive software management and a strong digital munications capabilities to plete the centralized operation, display, alarm, tasks such as printing and optimal control, avoiding Changgui instrument control is distributed difficulties after the manmachine contact, no unified management shortings, ensure that equipment running in top form.Here are distributed control systems with several concepts. direct digital control system (DDC) direct digital control system (Direct Digital Control referred to as DDC) shown in Figure 2. Computer through the analog input channels (AI) and digital input channels (DI) realtime data collection, and then calculated according to certain rules, and finally the control signals, and through the analog output channels (AO) and the switch output channel (DO ) direct control of the production process. So DDC system is a closed loop control system, a puter in the industrial production of the most popular way of an applicationDDC system control puter to undertake tasks, which required realtime, high reliability and adaptability. Composition of direct digital control systemDirect digital control system consists of the process input channel, process control puter, the process of output channels of three parts. Process input channels from the analog input and digital input of two parts. Analog input channels from the transmitter, the sampling switch, amplifier, A / D converter and interface circuit. One is the role of the transmitter signal will be converted into the standard nonpower electrical signal，Can be temperature, pressure, flow transformed into 010mA or 420mA DC signal, it is through the A / D converter to achieve. Digital input channels from the switch contacts, photoelectric coupler and interface circuit, reflecting the production process on / off state of the contact signal, through the optocoupler and the interface circuit transformation into a digital signal sent to the puterDirect mitment to the process control puter operations and control tasks, first of all input channels through the process of collecting the parameters of the object and signals, then the scheduled control law (such as PID) for operation, and then send control signals to the controlled object, then the output channel direct control of the control valve actuatorProcess output channel from the analog output and digital output of two parts. The former control of the puter output of digital signals into analog voltage or current signals, through the amplifier to drive the actuator control valve to achieve control of the production process. This part of the interface circuit, D / A converter, amplifier and actuator ponent. Which the puter output of the switch signal by amplifier to drive solenoid valve and relay actuator, which consists of electrical interfaces, optical coupler, amplifier and actuator ponent。Direct Digital Control System in accordance with the deviation of the ratio of the basic algorithm (P), integral (I) and differential (D) control, a continuous system technology is mature, the most widely used as a basic law, the PID control Guilv discrete implementation of and make puter, can easily be accumulated to use this proven technology, but also the alleged target of the mathematical model or parameter is not very clear under the circumstances, Jing Guoline tuning of Xiaoguo satisfactory. Therefore, the law regulating discrete analog digital PID algorithm, puter control of industrial processes have been widely adopted system, a DDC system, the basic algorithmDigital PID control algorithm, analog PID controller ideal formula for the type of e (t) deviation (set value and the actual output value of the error) u (t) control the amount of Kp Ti a scaling factor Integral time constant Td differential time constant transfer function written in t