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.