若 PLC 操控的體系需求聯(lián)入工廠主動(dòng)化網(wǎng)絡(luò)，則 PLC 需求有通訊聯(lián)網(wǎng)功用，即要求 PLC 應(yīng)具有銜接其他 PLC 、上位核算機(jī)及 CRT 等的接口。大、中型機(jī)都有通訊功用，目前大部分小型機(jī)也具有通訊功用。
（ 7 ）對(duì) PLC 結(jié)構(gòu)辦法的挑選
在相同功用和相同 I/O 點(diǎn)數(shù)據(jù)的狀況下，全體式比模塊式價(jià)格低。但模塊式具有功用擴(kuò)展靈活，維修便利（換模塊），簡(jiǎn)略判斷毛病等長(zhǎng)處，要按實(shí)踐需求挑選 PLC 的結(jié)構(gòu)辦法。

If the system controlled by PLC needs to be connected to the factory automation network, PLC needs to have the function of communication networking, that is, PLC should have the interface connecting other PLCs, upper accounting computers and CRTs. Both large and medium-sized computers have communication functions. At present, most small computers also have communication functions.
(7) Selection of PLC structure method
Under the condition of the same function and the same i/o point data, the price of all-in-one type is lower than that of modular type. However, the modular type has the advantages of flexible function expansion, convenient maintenance (changing modules), simple judgment of faults and so on. The structural method of PLC should be selected according to practical needs.