繪制各種電路的目的，是把系統(tǒng)的輸入輸出所設計的地址和名稱聯系起來。這是很關鍵的一步。在繪制 PLC 的輸入電路時，不僅要考慮到信號的連接點是否與命名一致，還要考慮到輸入端的電壓和電流是否合適，也要考慮到在特殊條件下運行的可靠性與穩(wěn)定條件等問題。特別要考慮到能否把高壓引導到 PLC 的輸入端，把高壓引入 PLC 輸入端，會對 PLC 造成比較大的傷害。在繪制 PLC 的輸出電路時，不僅要考慮到輸出信號的連接點是否與命名一致，還要考慮到 PLC 輸出模塊的帶負載能力和耐電壓能力。此外，還要考慮到電源的輸出功率和極性問題。在整個電路的繪制中，還要考慮設計的原則努力提高其穩(wěn)定性和可靠性。雖然用 PLC 進行控制方便、靈活。但是在電路的設計上仍然需要謹慎、全面。因此，在繪制電路圖時要考慮周全，何處該裝按鈕，何處該裝開關，都要一絲不茍。
4) 編制 PLC 程序并進行模擬調試
在繪制完電路圖之后，就可以著手編制 PLC 程序了。當然可以用上述方法編程。在編程時，除了要注意程序要正確、可靠之外，還要考慮程序要簡捷、省時、便于閱讀、便于修改。編好一個程序塊要進行模擬實驗，這樣便于查找問題，便于及時修改，好不要整個程序完成后一起算總帳。The purpose of drawing various circuits is to connect the address and name designed by the input and output of the system. This is a crucial step. When drawing the input circuit of PLC, we should not only consider whether the connection point of the signal is consistent with the name, but also consider whether the voltage and current at the input end are appropriate, and also consider the reliability and stability conditions under special conditions. In particular, it is necessary to consider whether the high voltage can be led to the input end of the PLC. If the high voltage is led to the input end of the PLC, it will cause great damage to the PLC. When drawing the output circuit of PLC, we should not only consider whether the connection point of output signal is consistent with the name, but also consider the load capacity and voltage resistance of PLC output module. In addition, the output power and polarity of the power supply should be considered. In the drawing of the whole circuit, we should also consider the design principles and strive to improve its stability and reliability. Although it is convenient and flexible to control with PLC. But the circuit design still needs to be cautious and comprehensive. Therefore, when drawing the circuit diagram, we should consider carefully where to install the button and where to install the switch.
4) Compile PLC program and conduct simulation debugging
After drawing the circuit diagram, you can start to compile the PLC program. Of course, you can program in the above way. When programming, in addition to paying attention to the correctness and reliability of the program, we should also consider that the program should be simple, time-saving, easy to read and easy to modify. A simulation experiment should be carried out to compile a program block, which is convenient for finding problems and modifying in time. It is best not to calculate the general ledger together after the completion of the whole program.