PLC inside the commonly used symbols are divided into: basic data, composite data, parameters, three categories.
1. Basic Data: Basic data refers to the data whose Word length is less than 2 words (32 bits), including bit, Byte, word, DoubleWord, ASCII character, Integer, Double Integer, etc. These data are in accordance with IEC 1131-3.
2. Composite data: Composite data refers to the data whose characters are longer than 2 characters (32 bits). The data can be combined by basic data.
3. Parameters In SIEMENS S7 PLC, the data transmitted between logic blocks are called parameters. The parameters of S7 are divided into "formal parameters" and "actual parameters".
Extended Information:
PLC control system, Programmable Logic Controller, programmable logic controller, an electronic device designed specifically for industrial production, which uses a class of programmable memory.
It is used to store programs internally, execute user oriented instructions such as logical operations, sequential control, timing, counting and arithmetic operations, and control various types of machinery or production processes by digital or analog input/output. It is a core part of industrial control.
It is a real-time system, unlike a personal computer. In the traditional motor control system based on relay, whenever the design is changed, the whole system almost has to be rebuilt, which is not only time-consuming but also laborious.
At the same time, due to the shortcomings of poor contact, wear and large size of the relay, the cost increases, the reliability is low, and the maintenance is not easy. In order to improve these shortcomings, DEC was first published in 1969: Programmable Controller.
