Car body storage and transportation line information management based on radio frequency identification system
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Preface
In recent years, with the rapid improvement and rapid development of the automation level of the manufacturing industry, the importance of information management in the production line has become more and more important. The diversity of products, the complexity of production processes, and the accelerated pace of product upgrading determine the continuous improvement of production information management methods and methods.
The basic condition of information management is: the products on the production line have an information carrier that can be marked with “own identity”. Only by correctly identifying the product type, variety and other information, can the process control of the production process be completed and various information management can be realized. As information carriers, barcodes, RFID (Radio Frequency Identification), etc. are more common. The code carrier (TAGS) in the radio frequency identification system is also often referred to as an electronic tag. Compared with other information carriers such as bar codes, electronic tags have the advantages of data readable and writable; low bit error rate; high temperature resistance; corrosion resistance; no need for optical visibility and other advantages to withstand harsh environments. Therefore, its application fields are very wide.
This article introduces an example of realizing the information management of the car body storage and transportation line in the car production process based on the radio frequency identification system and the electronic tag as the information carrier.
1 The overall composition of the system
The overall system is composed of a computer, RFID, information entry terminal, information query terminal and control PLC. The brief structure of the system is shown in Figure 1.
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Figure 1 System composition
(1) Computer: It is the data processing and management center of this system. Responsible for information management and control of production processes. Main hardware composition: CPU P4 2.4G; 100M Ethernet card. Software composition: INTOUCH 8.0; SQL SERVER2000.
(2) Control PLC: Control the operation of the entire production line and the completion of all the actions of getting on and off the car. Receive the starting, boarding and other instructions from the computer to it. The A2A CPU host of MITSUBISHI company is used in this system. It adopts bus control.
(3) Information input terminal: mainly completes the input of the information code of the online model. It is composed of display, terminal controller, keyboard and bar code reader. According to the different forms of the information code before going online, the information entry of each online point can be directly read by a barcode scanner, or it can be entered by the operator from the terminal keyboard at the online location. After the information code is entered, the specific vehicle type information currently entered is directly displayed on the terminal display at that location.
(4) Information query terminal: It can be any computer or terminal connected to the system via Ethernet. They are distributed in different functional departments, using switches and Ethernet as media to connect to the system.
(5) Radio frequency identification system: It is the information carrier of this system. It is mainly composed of a code carrier installed on the spreader that transports the body; an antenna (Antenna) for reading and writing code carrier data, a controller (Controller) that controls reading, writing and communication processing, and a network interface module (Bus Module). composition. The radio frequency identification system in this system uses the LRP820 of the American EMS company. Since the reading and writing of the code carrier by the identification system in this system is completed by the computer, the MM80 network interface module that supports the multipoint interface protocol (MUX32) is selected, which can connect 32 reading and writing devices. Connect directly to the computer through the Rs232 port.
2 System function
When the car body enters the storage and transportation line spreader, the terminal enters the model code, and the computer automatically writes this information into the code carrier after processing this information. Based on this, the computer can read this information through the RFID antennas installed at each offline point on the storage and transportation line and at each dump station to realize information management, and according to the production process flow, send instructions to the control PLC to complete Related operations and process control. After the car body is off the assembly line, the code carrier information on the spreader carrying the car body is set to be empty.
This system can realize the following main functions:
(1) Production management operations:
·Specify the storage area of the current online models.
·Online models are automatically classified and stored.
·Offline model selection.
· Turnover of body and empty spreader.
(2) Information statistical report management
·Real-time statistics on the number of online car models.
·Statistical report on the number of types of online and offline models.
·Statistical report of production information such as shift, day and month.
·Classification report counts the number of various models that have been produced, etc.
(3) Real-time monitoring of the production line
·Monitor the specific location of the current online model.
·Check the product information and online time of an online model.
·Conveying line and related equipment operation status and fault monitoring.
The computer monitoring and management of the entire storage and transportation line is an important part of the company’s local area network. In authorized functions. Relevant managers can access and query production information such as the model information on the production line and the number of offline models through the password authority, and print out the corresponding reports.
3 software design
In this system, the monitoring software uses Wonderware’s InTouch 8.0 configuration software. The InTouch device driver does not include the communication program with the LRP820 controller, so it is necessary to write the identification system communication program and the terminal entry and response terminal query programs.
EMS products provide standard communication protocols, and users can easily write communication programs between the computer and the RFID controller. Figure 2 is the command format for the computer to read a data block from the code carrier through the controller and the format of the data returned by the controller. In actual use, in many cases, it is not necessary to read all the data in the tag. According to the needs, the relevant station can only read a part of the relevant information. This can effectively shorten the length of read and write bytes. Correspondingly reduce the read and write time.
Figure 2 The command format to read a data block from the code carrier
Like reading data, writing data to the code carrier can also be one or more bytes. Figure 3 is the command format for the computer to write a data block to the code carrier through the controller. The programming is relatively simple, and the program list is omitted.
Figure 3 The command format for writing a data block to the code carrier
4 System reliability and stability constraints
Reliability is the life of any product and project. As a management method and control application, it is difficult to reflect its specific value without reliability and stability. The main factors affecting reliability and stability in this system are:
(1) The reliability of the source of the information code
Like other data acquisition systems, the reliability of the data source is the foundation. As the basis of the data source of this system, the reliability of the RFID system to read and write electronic tags is crucial to the stability and reliability of the overall system. The integrity of a read or write cycle; the installation of the code carrier; the influence of the surrounding metal and electromagnetic radiation on the reading and writing distance of the antenna to the code carrier are the main factors considered in the design.
(2) Reliability of software design
In multipoint communication, the complete processing of sending data, receiving data, and returning messages is particularly important, and it is directly related to the reliability of the system. After sending a read or write command to the controller, it is very necessary to judge whether the command is successfully executed according to the returned message.
LRP820 provides good application characteristics, enabling users to read the data in the code carrier while the target is moving, but in a multi-controller system, two or more code carriers enter the read and write state at the same time The situation will also appear, this is the redundant processing that must be provided in the software design process.
5 concluding remarks
Compare with other schemes that use PLC to read, write and manage radio frequency identification system. In a management system with a large amount of information and a wide variety of products, this solution has greater advantages. The computer eliminates a large amount of data exchange with the PLC. PLC is also freed from unlimited code data processing and replaced by computer database management.
Since the system was formally put into use in Liuxin Auto Stamping Co., Ltd. in 2003, the overall system operation status is stable, the radio frequency identification system reads and writes information is reliable, the system operation interface is friendly, and the operation is simple. It can effectively improve production efficiency and meet production and Management needs.
references
[1] Edited by Li Peng. “Computer Communication Technology and Program Design”. Xidian University Press.
[2] LRP820-Series Long-Range PassiveReader/Writers. EMS OPERATORS MANUAL.
[3] Read Only Node Setup Software. EMS USER’S GUIDE.
[4] Mitsubishi Corporation. <
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