1. The ability to take points is no longer critical, but communication ability is more important Now everyone can see that the control system architecture has been fully industrial Ethernet based. When field bus emerged more than a decade ago, we said that a high-end PLC should have distributed control capabilities, be able to carry many distributed sites, and have the ability to connect to field bus. At that time, when evaluating the performance of a controller, the ability to take points was the most important item. With the improvement of the intelligence of field devices and the need for control systems to ensure reliability, stability, and availability, the ability of the CPU to carry points is no longer the key to distinguish between high-end and non high-end devices. The focus now should be on the ability of Ethernet communication to cover the field, which directly determines the level of control of the system over field process equipment. At the same time, because we are now in a period of connecting the past with the future, for example, the field bus is still in use, and it cannot be said that due to the upgrade, it is no longer compatible with the field bus in the past. However, the future development trend is the world of Ethernet, and support for Ethernet should be more important, while compatibility with existing fieldbus protocols is also an aspect that cannot be ignored. Previously, Ethernet was a communication method only used for communication between PLC and upper management computer software. Its advantage is that it can transmit larger amounts of data, and more control stations can be connected to this network. However, for field control, even if there are many field I/O stations and devices, the communication volume is not as large as that between the PLC and the host computer. However, it requires higher real-time and reliability requirements, packet loss rate is very important, and real-time and data transmission verifiability are very important. Now, with the development of lean management in factories, more and more factories are using upper level operation and maintenance management software such as MES systems and asset management systems. Of course, some people also call it intelligent manufacturing or digital chemical plants. This is due to the fact that more and more process customers are beginning to pursue more lean control, hoping to obtain some on-site data through the PLC system for direct use, improving efficiency and real-time performance, thereby improving the overall operational efficiency and management ability. 2. PLC information security becomes indispensable In the case of "one network to the end", there is a problem involved: After the network is connected, and after the on-site production process equipment is connected to the above management software or even the cloud, it opens channels for some management and data analysis systems and dedicated systems for our industrial control, the requirements fo...

At first, PLC was mainly used for logic control of switching value. With the progress of PLC technology, its application field is expanding. Today, PLC is not only used for on-off control, but also for analog and digital control. It can collect and store data, and also monitor the control system; It can also be networked and communicated to achieve control and management across a wide range of regions. PLC has increasingly become an important role in the family of industrial control devices. 1. For on-off control The ability of PLC to control switching value is very strong. The number of input and output points controlled can be as few as ten or dozens of points, and as many as hundreds, thousands, or even tens of thousands. Because it can be connected to the Internet, the number of points is almost unlimited. No matter how many points can be controlled, the logic problems controlled can be varied: combined, sequential, real-time, delayed, non-counting, counting, fixed sequence, random work, and so on. The hardware structure of PLC is variable, and the software program is programmable. It is very flexible when used for control. If necessary, multiple sets or groups of programs can be written and called as needed. It is very suitable for the needs of multiple working conditions and multiple state changes in industrial sites. There are many examples of using PLC to control the switching value. Metallurgy, machinery, light industry, chemical industry, textile, etc., almost all industrial industries need it. At present, the first goal of PLC is that it can be easily and reliably used for the control of switching value, which is incomparable with other controllers. 2. For analog quantity control Analog quantities, such as current, voltage, temperature, pressure, etc., vary continuously. Industrial production, especially continuous production process, often needs to control these physical quantities. As an industrial control electronic device, if PLC can not control these quantities, it is a big deficiency. Therefore, PLC manufacturers have carried out a lot of development in this area. At present, not only large and medium-sized computers can carry out analog control, but also small computers can carry out such control. PLC shall be equipped with A/D and D/A units for conversion between analog quantity and digital quantity for analog quantity control. It is also an I/O unit, but a special I/O unit. A/D unit converts analog quantity of external circuit into digital quantity, and then sends it to PLC; The D/A unit converts the digital quantity of PLC into analog quantity and then sends it to the external circuit. As a special I/O unit, it still has the characteristics of anti-interference of I/O circuit, isolation of internal and external circuits, exchange of information with input/output relay (or internal relay, which is also an area of PLC working memory, readable and written), etc. A in A/D here is mostly current, or voltage, and also temperature. ...

Product introduction: Distributed I/O expansion interface module, integrated 8DI/16DC, switchable input/output, 24VDC, 0.5A transistor output; Distributed expansion is carried out through CS31 bus interface, and up to 7 local expansion modules can be expanded in a centralized way, including up to 4 analog local modules Product classification: PLC medium PLC interface module interface module Brand: ABB Product introduction: This module is the CS31 bus expansion interface module of AC500 PLC. While integrating the bus interface, it can also integrate 8 digital 24VDC inputs, and the other 16 points can be set as input or output in the programming software. If used as output, the output is 0.5A transistor output. After the module guide rail, 7 new modules can be expanded, but the analog module can be expanded up to 4.