Command Execution Program For Controller Board

- Aug 11, 2017-

     It is widely used in the field of industrial control. Before the advent of programmable logic controllers, it was common to use hundreds of relays and counters to form an automated system with the same functionality, and now the programming of simple programmable logic controller modules has largely replaced these large devices. Programmable Logic Controller System program in general before the factory has been initialized, users can according to their own needs to edit the corresponding user program to meet the different requirements of automated production.Controller Board
    The original programmable logic controller only has the function of circuit logic control, so it was named Programmable Logic Controller, and then with the continuous development, the original function of the computer module has been simple, including logic control, timing control, analog control, multiple computer communication and many other functions, the name changed to programmable controller. Input and output interface circuit, the field input interface circuit by the optical coupling circuit and the microcomputer input interface circuit, the function is the PLC and the field Control interface interface Input channel. The field output interface circuit is integrated by the output data register, the selection circuit and the interrupt request circuit, and the function plc outputs the corresponding control signal to the execution part of the scene through the field output interface circuit.Controller Board
    During the user program execution stage, the PLC always scans the user program (ladder diagram) sequentially by the order of the top and bottom. In the scanning of every a trapezoid diagram, but always first scan the left side of the ladder diagram of the control line composed of the contact points, and the first left and right, first up and down the order of the control circuit composed of the contact point logic operation, then, according to the result of the logical operation, the state of the corresponding bit in the system RAM storage area is refreshed, or the state of the corresponding bit in the I/O image area is refreshed, or whether the special function instruction specified in the ladder diagram is to be executed.Controller Board
    If you use immediate I/O directives during program execution, you can access the I/O points directly. Even with the I/o instruction, the input process image register value will not be updated, the program directly from the I/O module value, the output process image registers will be immediately updated, which is somewhat different from the immediate input.Controller Board

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