The hottest PLC network connection based on sysmac

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PLC network connection based on sysmacnet

PLC field communication network is an important direction of PLC development and application and current development, and it is also an important way to make PLC obtain greater benefits in the industrial field. At present, there are many kinds of fieldbus standards that can be implemented by communication low-voltage appliances. Among them, Omron SYSMAC net link system network is a multi position, multi manufacturer machine/production line control level network based on DeviceNet Fieldbus standard, which integrates control and data. As long as the equipment and components of different manufacturers or companies comply with the protocol, they can be connected to the network, so as to realize the connection between PLC and computer, PLC and PLC PLC and other manufacturers can communicate the control and communication between low-voltage appliances. The sysmac-c series programmable controller (PLC) of OMRON company not only has the function of sequence control, but also has the function of data communication, and the instruction system is compatible. Therefore, in order to achieve centralized management of information and decentralized control of functions in industrial automation control, a local network system (SYSMAC net link system) can be formed as required. The system is a special, parallel access, limited distance high-speed communication network, which can solve complex data communication problems. The equipment connected to the network can be computers, PLC, CNC machine tools and terminal equipment, so as to form a decentralized control system with PLC as an important component. This network system has the characteristics of simple operation and fast response. The functions of double loop, transmission test, loop structure and so on make it highly reliable and applicable. This paper mainly introduces the structure, system configuration and data transmission of SYSMAC net network connection system

1 structure of SYSMAC net network system

1.1 system composition

sysmac net network construction, survey, design, construction, supervision and other units and individuals involved will be doomed. The connection system is composed of a line server and up to 126 nodes. Each node can be a computer or PLC and other equipment with a network connection interface. The network system is shown in Figure 1. The system is connected by two optical cables, so it has strong anti-interference, and data communication can be carried out between any two nodes. The function of the line server in the network is to control the communication of the system. The network server board (NSB), network server (NSU) and network link unit (SNT) are all network connection interfaces. The network service board is the interface between the upper computer and the network connection system, which is directly connected with the computer CPU bus and exchanges information with the optical fiber network through high-speed DMA (direct memory access). The network server can be used not only as the interface between the upper computer and the network connection system, but also as the interface between PLC or other equipment and the network connection system. The network link unit is the interface between PLC and network system

the network connection system has two circuits, which are normal circuit and reverse circuit respectively. Whenever the normal circuit fails and cannot transmit data, the system will automatically use the reverse circuit to ensure that the system can continue to work normally. The maximum distance between nodes in the network connection is 1km, which can be more than 3km if a modem is used

multiple network connections can also be connected through bridge connectors to form a more advanced control system. A bridge connector is required between each two SYSMAC net network systems, and each system contains at most 20 bridge connectors, that is, the connection of multiple SYSMAC net network systems can only be less than 20 other network system connections. Figure 2 shows the connection system of two SYSMAC networks

1.2 system configuration

sysmac net network system commonly used devices and models are as follows:

1) line server model: s3200-lsu E

2) network service board (NSB) model: s3200-nsb11-e

3) network server (NSU) model: s3200-nsu AE

4) SNT model: c500-sn Nanjing Julong relies on its strong R & D technical strength, products with excellent comprehensive performance and comprehensive services t31-v3

5) bridge connector (NSU) model: s3200-nsu Ge

6) serial interface model: RS-232C

7) programmable controller (PLC) model: any model of sysmac-c series

8) the upper computer can be any type of personal computer or small computer. In the selection, it is best to choose the upper computer recommended by the PLC manufacturer, because they are equipped with rich support software for selection. These software include: re online/offline/remote programming function, data register/program register, i/o information reading/processing, PLC information reading/processing, file management, various monitoring and calendar, time, calculation function, etc. If the user chooses the upper computer, it is necessary to configure the communication interface hardware and compile the communication application program

2 data transmission of SYSMAC net network system

network read and write instructions enable PLCs in the network system to transmit data to each other according to peer-to-peer communication protocol. That is, there are two devices in the system. When one device is the source, the other device is the target. When the source device starts communication, the source sends an inquiry signal to the target. If the target device is not busy, the control word code is used to continuously send the data bit by bit to the target device. If the target device is busy, the source device will send an inquiry signal 32 times in a row. If there is no answer, it will automatically exit the communication subroutine

3 conclusion

to sum up, the SYSMAC net network connection system composed of PLC and upper computer can not only complete their respective logic and sequence control functions, but also quickly and accurately read the i/o status of PLC, the contents of timer/counter and register to reduce the existing unstable friction force, CPU running status and user program into the memory or register of upper computer through the network. At the same time, the above contents can also be written into the corresponding memory or register of PLC through the upper computer. The upper computer can collect, analyze, tabulate and print the data of PLC. Truly achieve centralized management of information and decentralized control of functions, so as to achieve

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