輸入接線：輸入接線一般不要太長。但假如環(huán)境煩擾較小，電壓降不大時，輸入接線可適當(dāng)長些；輸入／輸出線不能用同一根電纜，輸入／輸出線要分隔；盡或許選用常開觸點(diǎn)方式聯(lián)接到輸入端，使編制的梯形圖與繼電器原理圖一致，便于閱覽。
輸出聯(lián)接：輸出端接線分為獨(dú)立輸出和公共輸出。在不同組中，可選用不同類型和電壓等級的輸出電壓，但在同一組中的輸出只能用同一類型、同一電壓等級的電源。由于PLC的輸出元件被封裝在印制電路板上，并且聯(lián)接至端子
端子一般指由銅材等沖制而成的聯(lián)接器接觸件。端子是聯(lián)接電氣線路的常用元件，首要在器材與組件、組件與機(jī)柜、系統(tǒng)與子系統(tǒng)之間起電聯(lián)接和信號傳遞的作用，并且盡量保持系統(tǒng)與系統(tǒng)之間不發(fā)作信號失真和能量丟掉的改變.
板，若將聯(lián)接輸出元件的負(fù)載短路，將焚毀印制電路板。選用繼電器輸出時，所承受的電感性負(fù)載的大小，會影響到繼電器的運(yùn)用壽命，因此，運(yùn)用電感性負(fù)載時應(yīng)合理挑選，或加隔絕繼電器。PLC的輸出負(fù)載或許發(fā)作煩擾，因此要采用辦法加以控制，如直流輸出的續(xù)流管保護(hù)，交流輸出的阻容吸收電路，晶體管

Input wiring: input wiring is generally not too long. However, if the environmental disturbance is small and the voltage drop is not large, the input wiring can be appropriately longer; Input / output lines cannot use the same cable, and input / output lines should be separated; The normally open contact mode may be used to connect to the input end as far as possible, so that the ladder diagram compiled is consistent with the relay schematic diagram, which is easy to read.
Output connection: the output terminal wiring is divided into independent output and common output. In different groups, the output voltage of different types and voltage levels can be selected, but the output in the same group can only use the power supply of the same type and voltage level. Since the output components of PLC are encapsulated on the printed circuit board and connected to the terminal
The terminal generally refers to the connector contact made of copper, etc. Terminals are commonly used components for connecting electrical circuits. They mainly play the role of electrical connection and signal transmission between equipment and components, components and cabinets, and systems and subsystems, and try to keep the changes of signal distortion and energy loss between systems
If the load connecting the output components is short circuited, the printed circuit board will be burned. When selecting the output of the relay, the size of the inductive load it bears will affect the service life of the relay. Therefore, when using the inductive load, it should be reasonably selected or isolated relay should be added. The output load of PLC may be disturbed, so measures should be taken to control it, such as freewheeling protection of DC output, resistance capacitance absorption circuit of AC output, and transistors