PLC is also called programmable logic controller, there are more and more kinds and brands of PLC in the market, and their application fields are more and more widely, PLC plays a more and more important role in industry control especially in sequential control, it has no substitute in the foreseeable future. Generally manufacturers will write the software for PLC before it leaves the factory, but frequently we need to rewrite the PLC program to meet production requirements. This requires our software engineers to develope a good habit in daily programming. No one can draw a square and a circle without proper tools, following are the basic steps of PLC software programming:
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