The Design And Implementation Of Multi-channel I/O Device

With the continuous development of industry, Industrial control system is becoming more and more powerful, External devices is more and more.The external devices is connected with the computer through I/O device.Computer send orders to complete the control of other devices. So the number of I/O port as much as possible, IO ports can be configured flexibly,have stronger anti-interference ability,have standard communication interface,cost-effective.According to the industrial control field with low cost,high reliability,high stability,we design a master-slave mode on singlechip STC12C5A60S2.The device is composed of main board and secondary board.Main board receive the massage come from the host computer,and send it to the secondary board, at the same time the main board send message to the host compter come from the secondary board.The secondary board choose the IO mode, send it to main board,and complete the task from main board.We present the detailed communication interface design for the main board and the secondary board.the main board circuit include power-supply module,RS485,E2PROM expander circuit, address selection.The secondary board include the design of I/O port,DA output,address selection and communication protection etc.The software design is on Keil c51platform,use MODBUS communication protocol, divided into main program and secondary program.The main program including the communication with host computer and secondary board, configuration program of I/O.The secondary program including the communication with main board,scanning outside, DA output etc.After these works run a test on I/O device,the test including output and input.The device is used for simulating the works of coal-fired power station,the system runs smoothly,meet the control requirement.