How to design machine tool controlled by PLC

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How to design a machine tool controlled by PLC

1 know the working principle of PLC

programmable controller is also referred to as PLC. Similar to the relay system, PL formulates a scientific and fair fault handling scheme. C is also composed of input part, logic part and output part. The input part collects and stores the actual operation data of the controlled part, and the logic part processes the information obtained by the input part, And determine which functions require output response. The output section provides which of the many devices being controlled need real-time operation processing. PLC adopts microprocessor and memory composed of large-scale integrated circuit to form logic part. Although the function of the logic part is similar to that of the relay control system, its composition, working principle and operation mode are quite different from the former. Through programming, the control program can be changed flexibly, which is equivalent to changing the hardwired circuit of the relay. This is the so-called programmable

2 master the language and instructions of PLC

after knowing the working principle of PLC, it is easier to understand its language. The most common PLC languages are ladder diagram and statement table. The ladder diagram is the most intuitive and easy to use. For a detailed understanding, you can read the relevant teaching materials. It should be emphasized that although the principles are the same and the basic instructions are similar, the command symbols of PLC bow rings fixed at the lower part of the middle crossbeam vary from manufacturer to manufacturer. For example, the products of Mitsubishi are represented by PLS, while Omron is called Difu, while Siemens is │ P │. These specific differences depend on the programming manuals of various products

3 learn to use various programming software

after a program is compiled, it should be input into the PLC. In the past, hand-held programmers were mostly used, and manual input was required, which was troublesome and easy to make mistakes. In recent years, with the popularization of computer, it has been gradually replaced by various programming software. For example, winproladder software of Yonghong company and cx-programmer of Ohm company. Step-7-micro-win32 of Siemens, etc. These tools and software can be run under the environment of windows, which is very convenient to use. When you select a factory PLC, you must learn to use its programming software, because it will greatly save your programming and debugging time. Take winproladder software of Yonghong company as an example. When programming, it can provide you with the input range of operands and quickly search for special instructions. The statement table is automatically generated according to the ladder diagram, and the syntax errors are pointed out. During debugging, the program is quickly and accurately transmitted to PLC through the data line, and then the execution status is monitored. Each input and output point can be forcibly set/reset. It can also be done. In short, when you master the use of programming software. Will be able to accomplish the design task with half the effort

4 understand the signals controlled by PLC.

plc controls the output signal according to the input conditions. The input signal is the button on the console, the limit switch on the machine tool, the pressure relay, the photoelectric switch and other sensors. The output point controls the on-off of the relay or contactor coil, the on-off of the indicator light, the engagement of the solenoid of the hydraulic pressure valve and the output of the signal terminal of the frequency converter. When designing a machine tool, we often encounter two problems. One is that the PLC has limited expandable i/o points, and the other is that increasing the i/o points means increasing the cost. Therefore, we need to know what the control signals are, how many are they, and how many input and output points are needed, so as to select the PLC

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