The lighting system on campus is a prerequisite for the school's teaching, research and other aspects of normal work. Establishing a reliable lighting monitoring system can improve the quality of school management, improve the quality of school lighting systems, and bring convenience to lighting equipment, lighting maintenance and maintenance, and save energy. School lighting can be generally divided into: teaching buildings, libraries and other teaching lighting, street lighting and other public places lighting, student dormitory area lighting. These three parts have different functions and different lighting requirements. In school, the electric energy consumed by lighting accounts for a large proportion of the total energy consumption. In order to improve the reliability of the lighting system and reduce the energy, we propose a lighting distributed monitoring system solution. The upper computer selects the general PC, the control level. The high-performance single-chip microcomputer produced by Motorola is used for data communication using serial communication.
1 Design of campus lighting monitoring network The lighting power system design of each building and public place is designed according to the different functional needs of each building, and the power distribution plan, lighting power distribution equipment and lamps are selected. Generally, the 380V power supply comes out from the substation to each building. The total lighting distribution box of the object or place is sent to the lighting switch cabinet. We installed a monitor composed of single-chip microcomputers on each lighting switchgear to realize data communication, detection and control functions. Each monitor is connected to the upper PC. The weak current system forms a distributed lighting monitoring system.
1. 1 Network composition structure The lighting monitoring network structure adopts a tree structure. The distance between the main control room computer and each lighting switchgear controller is not very far. The wired asynchronous full-duplex communication mode is adopted, and the network structure is shown in Figure 1.
The main control room management level computer adopts PII266M Hz, and the computer can use the expansion card to reach up to 8 asynchronous communication lines of the Journal of Zhejiang Economic College, and each communication line can connect up to 255 lighting switchgear monitors, in order to reduce the cost communication. The line adopts ordinary three-core shielded cable, the communication is transmitted by baseband signal, the baud rate is 1200Bits /S, and the communication distance is 2km. The main control room manages the operating parameters of the lighting system through the computer, and carries out the measurement and control of each lighting switch cabinet. Monitoring and control.
1. 2 network communication protocol Because the communication data volume and frequency of the main control room computer and lighting switchgear of the lighting monitoring network are very small, the communication mode is adopted. The format of the communication data frame is as follows: (1) The main control room computer instruction data frame format: address instruction data byte (0 8) checksum each byte has the following meaning: address: the address code of the corresponding lighting switch cabinet measurement controller, 8 Bit.
Instruction: The instruction code for the corresponding control cabinet computer to perform the corresponding operation for the main control room computer, 8 bits.
Data Byte: Depending on the instruction, the number of bytes is 0 8 bytes.
Checksum: Accumulates all bytes, excluding carry, 8 bits.
(2) Lighting switchgear damper response, alarm and return lighting status parameter data frame format: type flag address data byte (1 7) checksum meaning of each byte is as follows: type flag: used to distinguish lighting switchgear controller The type of data reported, 8 digits.
EE: Indicates the response data received after receiving the computer command from the main control room.
Indicates the alarm information reported to the main control room computer after the fault is detected or the fault is detected by the lighting switchgear.
After the lighting switchgear controller completes the opening and closing of the lighting circuit, it reports to the lighting state of the main control room computer.
Address: the address code of the lighting switchgear's own controller, 8 bits.
Data Byte: Depending on the response, alarm, and return illumination status parameters, the corresponding number of bytes is 1 7 bytes.
Checksum: Accumulates all bytes, excluding carry, 8 bits.
2 lighting switch cabinet measurement and control device communication interface design lighting switch cabinet measurement and control device controller is the core of a high-performance, low-power 8-bit single-chip computer produced by Motorola can realize the setting, modification, detection, opening, Lighting equipment control, faults Zhejiang University College of Economics detection, alarm, using its asynchronous serial communication port (SCI) and the main control room computer for communication.
The communication interface between the main control room computer and the measurement and control device of the lighting switchgear is the same. The following describes only the design principle of the communication interface of the measurement and control device of the lighting switchgear.
2. 1 hardware design lighting switch cabinet measurement and control device measurement and control device communication interface circuit composition as shown in Figure 2: PB4 = 1, the relay J is released, the communication port sender and the communication cable can not send any data. PB4= 0, the relay J is sucked, and the transmitting end of the communication port is connected with the communication cable. At this time, if the logic level of point A is 0, the data output B is locked, and the D4 is turned on to make the transmitting end of the communication port be in a high resistance state, prohibiting Send data If the logic level of point A is 1, open data output port B, D4 is cut off, and allow data on TDO to be sent to transmission line T.
To start the SCI serial port occupying the transmission line T LIN E, first set PB4 = 0, so that the communication port transmitter end is connected with the transmission line T LINE, and then check the transmission line status, that is, set PC7 = 1, PC6 sends a negative pulse (see the figure Clear the Q end of IC1A to 0. After waiting time, check PC5. If PC5 = 1, it means that the extension has occupied the transmission line T LIN E. Even if the data is sent, because Q = 1 makes point A 0, the data is locked. At output B, data cannot be sent to transmission line T LIN E. If PC5 = 0, it means that the transmission line T LIN E is idle, M C68HC705C9A will set PC7 to 0, and open the data output port B. Since PC7 = 0, IC2A always outputs 0, at this time, the signal on the transmission line T LINE cannot cause the CLK of IC1A. The end is turned from 0 to 1, and the Q end of IC1A is always 0. The extension occupies the transmission line. This prevents two or more lighting control cabinets from measuring and controlling the controller and simultaneously occupying the transmission line T LINE to transmit data, resulting in damage to the transmitting end. After the extension sends the data, set PC7=1, PB4=1 to lock the data output port B, and disconnect the communication port from the communication cable.
2. 2 software design lighting switch cabinet measurement and control device communication interface using interrupt combined with receiving data pointer, counting to achieve the command and data reception of the main control room computer, after receiving a complete instruction, set the corresponding instruction flag, in the main Determine the type of instruction in the loop program and then perform the corresponding operation. The data transmission uses the query method to implement the data transmission function.
3 Network anti-interference design In order to improve the stability and reliability of the network and the operation of the lighting control cabinet, the following anti-interference measures are adopted in the design: (1) The main integrated circuit chip and components of the lighting switchgear are selected for industrial grade. Low power consumption.
(2) In the lighting switchgear, the high-power and weak-powered wires are separately routed, and the detection, control ports and communication ports are all optically isolated.
(3) The lighting switchgear controller uses the internal W ATCHDOG function of the M CU to prevent the program from running and crashing.
(4) There is a relay between the transmitting end of the communication port of the lighting switchgear and the communication cable, so that when the transmitting end of the communication port of a lighting switchgear is damaged even when the whole machine is damaged, it will automatically disconnect from the communication cable, which will not affect The normal operation of the network.
(5) Add the timing reset communication data receiving pointer, counter and data buffer address in the lighting switchgear controller program to prevent communication interruption.
(6) Add a checksum byte after each group of communication to improve the error detection capability.
4 Conclusion The campus lighting monitoring network proposed by the design scheme has the characteristics of large coverage, flexible networking and easy expansion. The network can be applied to the monitoring and management of campus street lamps, classrooms and dormitory buildings, and improve the integrity of each lighting system. Strengthen the lighting management ability of teaching buildings and dormitory buildings. On the other hand, the setting of midnight lights can save energy and have economic benefits.
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