控制規(guī)模還與輸入、輸出電路數(shù)有關。如控制規(guī)模為1024點，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點總是有數(shù)的。所以，規(guī)模大，所使用的模塊也多?？刂埔?guī)模還與PLC指令系統(tǒng)有關。規(guī)模大的PLC指令條數(shù)多，指令的功能也強，才能應付對點數(shù)多的系統(tǒng)進行控制的需要?？刂埔?guī)模是對PLC其它性能指標起著制約作用的指標；也是PLC劃分為微、小、中、大和特大型5.3組成模塊PLC的結構雖有箱體及模塊式之分，但從質(zhì)上看，體也是模塊，只是它集成了更多的功能。在此，不妨把PLC的模塊組成當作所有PLC的結構性能。這個性能含義是指某型號PLC具有多少種模塊，各種模塊都有什么規(guī)格，并各具什么特點。一般講，規(guī)模大的PLC，檔次高的PLC模塊的種類也多，規(guī)格也多，反映它的特點的性能指標也高。但模塊的功能則單一些。相反，小型PLC、檔次低的PLC模塊種類也少，規(guī)格也少，指標也低。但功能則多樣些，以至于集成為箱體。組成PLC的模塊是PLC的硬件基礎，只有弄清所選用的PLC都具有那些模塊及其特點，才能正確選用模塊，去組成一臺完整的PLC，以滿足控制系統(tǒng)對PLC的要求。

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 composition module
Although the structure of PLC can be divided into box and module, the box is also module in quality, but it integrates more functions. Here, it is advisable to regard the module composition of PLC as the structural performance of all PLCs.
This performance meaning refers to how many modules a certain type of PLC has, what specifications each module has, and what characteristics each has.
Generally speaking, for large-scale PLC, there are many kinds and specifications of high-grade PLC modules, and the performance indicators reflecting its characteristics are also high. But the function of the module is simpler. On the contrary, small PLC and low-grade PLC modules have fewer types, specifications and indicators. However, the functions are more diverse, so that they are integrated into the box.
The modules that make up the PLC are the hardware basis of the PLC. Only by understanding which modules the selected PLC has and their characteristics, can the modules be correctly selected to form a complete PLC to meet the requirements of the control system for PLC.