控制規(guī)模代表PLC控制能力，看其能對多少輸入、輸出點(diǎn)及對多少路模擬進(jìn)行控制?？刂埔?guī)模與速度有關(guān)。因?yàn)橐?guī)模大了，用戶程序也長，執(zhí)行指令的速度不快，勢必延長PLC循環(huán)的時間，也必然會延長PLC對輸入信號的響應(yīng)。為了避免這個情況，PLC的工作速度就要快。所以，大型PLC的工作速度總是比小的要快?？刂埔?guī)模還與內(nèi)存區(qū)的大小有關(guān)。規(guī)模大，用戶程序長，要求有更大的用戶存儲區(qū)。同時點(diǎn)數(shù)多，系統(tǒng)的存儲器輸入、輸出的信號區(qū)（輸入輸出繼電器區(qū)或稱輸入、輸出映射區(qū)）也大。這個區(qū)大，相應(yīng)地內(nèi)部器件（解釋見后）也要增多，這些都要求有更大的系統(tǒng)存儲區(qū)。控制規(guī)模還與輸入、輸出電路數(shù)有關(guān)。如控制規(guī)模為1024點(diǎn)，那就得有1024條I/O電路。這些電路集成于I/O模塊中，而每個模塊有多少路的I/O點(diǎn)總是有數(shù)的。所以，規(guī)模大，所使用的模塊也多。控制規(guī)模還與PLC指令系統(tǒng)有關(guān)。規(guī)模大的PLC指令條數(shù)多，指令的功能也強(qiáng)，才能應(yīng)付對點(diǎn)數(shù)多的系統(tǒng)進(jìn)行控制的需要。控制規(guī)模是對PLC其它性能指標(biāo)起著制約作用的指標(biāo)；也是PLC劃分為微、小、中、大和特大型5.3組成模塊PLC的結(jié)構(gòu)雖有箱體及模塊式之分，但從質(zhì)上看，箱體也是模塊，只是它集成了更多的功能。在此，不妨把PLC的模塊組成當(dāng)作所有PLC的結(jié)構(gòu)性能。

The control scale represents the control ability of PLC. It depends on how many input and output points it can control and how many analog circuits it can control. The control scale is related to speed. Because the scale is large, the user program is long, and the speed of executing instructions is not fast, it is bound to prolong the PLC cycle time, and it is bound to prolong the PLC response to the input signal. In order to avoid this situation, the working speed of PLC should be fast. Therefore, the working speed of large PLC is always faster than that of Small PLC. The control scale is also related to the size of the memory area. Large scale and long user program require a larger user storage area. At the same time, the number of points is large, and the signal area of memory input and output (input and output relay area or input and output mapping area) of the system is also large. This area is large, and the internal devices (see explanation later) will also increase, which requires a larger system storage area. The control scale is also related to the number of input and output circuits. If the control scale is 1024 points, there must be 1024 i/o circuits. These circuits are integrated into i/o modules, and there are always a number of i/o points in each module. Therefore, the scale is large and there are many modules used. The control scale is also related to the PLC instruction system. The large-scale PLC has a large number of instructions and strong functions, so it can meet the needs of controlling the system with many points. Control scale is an index that restricts other performance indexes of PLC; PLC is also divided into micro, small, medium, large and extra large 5.3 modules. Although the structure of PLC can be divided into box and module, from the qualitative point of view, the box is also a module, but it integrates more functions. Here, it is advisable to regard the module composition of PLC as the structural performance of all PLCs.