The following is a rough ranking of the performance of common series of Siemens PLCs, from low to high:
Small PLC
S7-200 Smart Series:
Suitable for simple small control systems, such as single-machine equipment control, local control of small production lines, etc. The processing speed is relatively slow, such as the execution time of bit instructions is usually at the level of tens of microseconds, and the memory capacity is limited, generally between tens of KB and hundreds of KB, which can meet the needs of simple logic control and small amounts of data processing.
It has the characteristics of low cost, small size, and easy expansion. It supports a variety of communication interfaces, such as RS232, RS485, etc., and can be connected to other devices for basic communication.
Medium PLC
S7-1200 Series:
It can be used for small and medium-sized control systems. It has a certain improvement in data processing capabilities and control speed compared to the S7-200 Smart series. The execution time of bit instructions is generally around a few microseconds to more than ten microseconds, and the memory capacity can reach about 1MB. It has strong scalability and supports a variety of expansion modules. It can meet more complex logic control and a certain scale of data processing.
The streamlined modular design reduces costs and maintenance difficulties, supports multiple programming languages and tool software, and facilitates user programming and control.
S7-300 series: Although it has been discontinued, it still has a certain amount of inventory and application in the market. This series is similar to the S7-1200 series in performance, but is more powerful in scalability and communication functions. It is suitable for medium-sized control systems with high performance and reliability requirements. It has a fast processing speed and can meet complex logical operations and medium-scale data processing needs.
Large PLC
S7-400 series:
Suitable for large control systems, with powerful processing capabilities, high-performance processors, high-speed control and data processing, bit instruction execution time can reach sub-millisecond level, large memory capacity, strong scalability, support for a variety of expansion modules, and can meet the needs of large-scale and complex control tasks.
It has a fail-safe function and redundant design to ensure that the system is stable and reliable. It is suitable for occasions with extremely high reliability requirements, such as large-scale chemical, electric power, metallurgical and other industries. Automation control system
S7-1500 series:
It is one of Siemens’ most advanced PLC product series. Its performance has been further improved compared with the S7-400 series. The bit instruction processing time of some high-end CPUs can reach nanoseconds, such as 1ns for 1518-4PN. It has larger memory capacity, better scalability and compatibility, and can meet the needs of complex and high-speed control tasks.
It has redundant design, supports multiple communication interfaces and protocols, and has powerful programming functions. It can achieve more efficient automation control and more complex process requirements. It is suitable for medium and large control systems, especially high-end application scenarios with extremely high performance, reliability and safety requirements.
