QnQ series PLC and security logic system

Abstract: QnQ series PLC and security logic system of information produced by excellent flow meter, flow meter manufacturer to offer you the quotation. 1 introduction safety logic system ( Also called safety protection system) In traditional industrial automation control system, through the integration of process control system of interlocking logic part. With the improvement of industrial technology level, to the big modern production process. More flow meter manufacturers choose model price quote you are welcome to inquire, here is QnQ series PLC and security logic system the article details. 1 introduction safety logic system ( Also called safety protection system) In traditional industrial automation control system, through the integration of process control system of interlocking logic part. With the improvement of industrial technology, modern production process to the direction of large-scale, complicated, limit development, more and more the various links in the process of production, failure happens, the risk of fire or explosion also increase, so must provide a highly reliable safety protection, safety logic system to be isolated from the process control system such as ( DCS） And alone. International authoritative institutions have also formulated a series of safety standards and rules, the rules must be strictly separated from the DCS and the safety logic system. Industrial process of security systems can be divided into three levels, level 1 for the engineering design and equipment selection, layer 2 for the process control system, the third layer in the logic system of safety and gas detection systems, as shown in figure 1. Industrial process equipment in the engineering design, equipment selection and installation of the early zui stage, such as to consider the safety of the operation, so the production device itself constitutes a security line of defense. But the lower the risk of far doesn't satisfy the need of actual production; On top of this, the process control devices such as DCS, for continuous dynamic control of the process, make the unit operating smoothly under the set value. Process control system, therefore, the device and reduces the risk of a class, this is the second line of defense. On process control, independent of process control system of the safety logic system, monitoring of production process, reduce the possibility of accident to low zui, ensure that operators in zui small, field operation is acceptable risk, it constitutes a system zui solid line of defense after zui. 2 qna series PLC is introduced. 1 system introduction QnA series PLC is Japan's mitsubishi company zui new, high-performance products. In the aspect of hardware, introduced many new QnA series PLC module, and almost all came from A and AnS series modules are completely compatible. In the aspect of communications, QnA series PLC with MELSECNET fully functional, and can support Ethernet network, control and communication links, and many other network protocols. The key point, QnA series PLC can be configured to double redundancy system, thereby improving the mitsubishi PLC can't do the shortcoming of redundancy and increase the reliability and availability of the system. 2. 2 QnA series PLC redundancy configuration QnA series PLC can be configured to a CPU, power supply, bus are redundant system. This configuration of simple structure, reliable performance, low cost, high performance/price ratio, as shown in figure 2. When master PLC CPU module is in normal and remote I/O control, control of PLC CPU module also it in the implementation of the program, and to accept the remote I/O data through the network, but it doesn't send data to control the remote I/O. Both CPU perform their program, but not at the same time. Network devices (B/W Communications register) Used for data exchange between the CPU. In the process of each network scan the B/W up to 2 k group from their respective CPU transferred to another CPU. Master control module of PLC and the control of PLC network is active. When failure occurs, the master PLC system control by PLC master switch to control PLC, enables the system to continue running. The whole process of switching time is about 1 s. Master PLC fault mainly has: ( 1) The master PLC power decline; （ 2) Master PLC CPU detects a fatal error, the CPU can't continue to run; （ 3) Master control module and PLC network communication equipment. 3 with the safety logic system of real engineering example of shenzhen automation project in zhanjiang new NPK fertilizer plant projects, to undertake the main DCS engineering and security logic systems engineering, and choose mitsubishi QnA series PLC as the main body of the project safety logic system equipment. NPK plant safety logic system on the function and process control system ( DCS） Completely separate, installation into a separate cabinet in the control room. When using SELSECMEDOC software programming, the use of programmable fail-safe logic. So-called fail safe, it is to point to in normal working conditions ( “ Health & throughout; ） , the system is controlled by relay and electromagnetic valve electrically charged, belong to the system of contact, the switch is closed.

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