2.AIW2 represents the address of the second analog channel on S7-200.

3.AIW4 represents the address of the fourth analog channel on S7-200.

4.PLC converts analog values into digital values of 1 word (16 bits), which can be accessed by area identifier (AI), data length (W) and byte start address.

5.EM235 is an analog expansion module of Siemens PLC, which has four inputs and 1 outputs, and various range settings. The range can be set to 0-5V through the internal DIP switch.

6. The four die-in channels respectively correspond to Aiw0, Aiw2, Aiw4 and Aiw6 in the program (of course, there is no die-in channel or module in the upstream), all of which are plastic, each accounting for 2 bytes, and the range of 0-5V corresponds to 0-32000 (unipolar).

Extended data

1, Siemens PLC products include LOGO, S7-200, S7- 1200, S7-300, S7-400, S7- 1500, etc. Siemens S7 series PLC has the advantages of small size, high speed, standardization, network communication, more powerful function and high reliability. ?

2.S7 series PLC products can be divided into micro PLC (such as S7-200), small PLC with performance requirements (such as S7-300) and PLC with medium and high performance requirements (such as S7-400).

3.PLC: planar optical waveguide (technology). The so-called planar optical waveguide means that the optical waveguide is located in a plane. PLC splitter is made of silicon dioxide, and PLC technology involves a wide range of materials.

4.SIMATIC S7-400 PLC S7-400 PLC is a programmable controller used in the middle and high-end performance range. S7-400 PLC adopts modular fanless design, which is reliable and durable. At the same time, you can choose multi-level CPU (function upgrade step by step).

5, and equipped with a variety of general function templates, so that users can combine into different special systems according to their needs. When the scale of the control system is expanded or upgraded, the system can be upgraded and fully meet the needs as long as some templates are appropriately added.

6. After 6.PLC is put into operation, its working process is generally divided into three stages, namely, input sampling, user program execution and output refresh. The completion of the above three stages is called a scanning cycle. In the whole operation process, the CPU of PLC repeatedly executes the above three stages at a certain scanning speed.

7.PLC does not need a large number of mobile components and wired electronic components. Its connectivity is greatly reduced. At the same time, the system maintenance is simple and the maintenance time is short. Plc is designed by a series of reliability design methods.

8. For example, redundant design. Power failure protection, fault diagnosis and information protection and recovery. PLC is a control device specially designed for industrial production process control, which has simpler programming language and more reliable hardware than general computer control. A simplified programming language is adopted. The programming error rate is greatly reduced.

References:

Baidu encyclopedia-Siemens PLC

Baidu encyclopedia -PLC