| With the development of information and network, the more and more parameters of process control in industry use the Field Bus technique, one of that, CAN-bus has come into wide use because of its superiority properties.According to an actual problem of monitoring water level at a pump station, this thesis proposes and designs a system used the CAN-bus as the mean of data transmission. The system can do real-time collect and display water level of a pool in pump station and also give an alarm signal if the water level exceeds the upper or lower safety limit of water level, so that electric pump at pump station can be controlled on or off. This system is used as a node of local data acquisition and monitoring in a distributed CAN network, and it is easy to be expanded by using CAN-bus for composing distributed data acquisition, transmission system. This builds the basis of realizing further networking management for enterprises.This system consists mainly of local water level data acquisition, single chip computer, data display, alarm, CAN-bus protocol node unit, etc. The water level data is processed in microcontroller AT89C52 through 12 bits serial A/D conversion anddisplayed in real-time by LED. If water level exceeds the safety limit of water level, the system gives an alarm signal and then sampled data will be transmitted on CAN-bus when converted in format using CAN protocol conversion chip SJAlOOO.In CAN network other nodes can receive data sent from this node and this node can receive data from other nodes also. So multi-host transmit mode is realized in CAN network.In order to decrease volume of system hardware and improve stability and reliability of system operation, the circuit structure, devices and PCB design used in this system are considered carefully, such as "watchdog" monitoring and digital filter in software. The software programmed by C language adopts a modular structure for decreasing volume of software, improving code efficiency and reliability of operation. |
PDF Full Text Request