PLC Overview 5: PLC Classification

PLC (Programmable Logic Controller) can be classified according to its function, structure, application field and IO point capacity. Common classification methods include the following:

1. According to functional classification (low, medium, high):

(1) Basic PLC: Suitable for simple control tasks, such as switch control, sequential control, etc.

(2) High-performance PLC: suitable for complex control tasks such as motion control, process control, etc.

2. Classification by structure:

(1) Modular PLC: It consists of multiple independent modules, each of which has independent input and output interfaces and processing capabilities.

(2) Integrated PLC: All input and output interfaces and processors are integrated on one chip.

3. Classification by application field:

(1) Industrial Automation PLC: Widely used in various industrial automation control systems, such as machine tools, production lines, robots, etc.

(2) Building automation PLC: used in building automation systems, such as air conditioning, lighting, security, etc.

(3) Traffic control PLC: used in transportation systems, such as subways, highway toll stations, etc.

(4) Medical equipment PLC: used in medical equipment, such as surgical instruments, medical electronic instruments, etc.

4. Classification by IO point capacity (this classification changes over time and is uncertain):

(1) For small PLCs, the number of IO points is generally less than 128 (256).

(2) Medium-sized PLC adopts a modular structure and its IO points are between 256 and 1024 (2048) points.

(3) Large PLC, IO points are above 1024 (2048).