基于PLC应用的一个监测和控制平台的开发公式外文翻译、中英对照、英汉互译

《基于PLC应用的一个监测和控制平台的开发公式外文翻译、中英对照、英汉互译》由会员分享，可在线阅读，更多相关《基于PLC应用的一个监测和控制平台的开发公式外文翻译、中英对照、英汉互译（33页珍藏版）》请在装配图网上搜索。

1、英 文 翻 译专 业：机械设计制造及其自动化英文翻译一 英文Development of a monitoring and control platformfor PLC-based applicationsAbstractThis paper discusses the design and implementation of a platform to remotely monitor and control PLC-based processes over TCP/IP or by using the GSM network. The platform is built using in

2、dustry-standard off-the-shelf PLCs. Integrated with each PLC are communication processors that can be used for connectivity to the network and to a GSM modem. The communication processor module (Ethernet module) used in this work,provides an industrial compatible protocol over TCP/IP that achieves t

3、he same functionality as Profinet but at a much higher bandwidth (10/100 Mbps).Additionally, a mobile-based communication protocol that facilitates remote monitoring and control of PLCs using SMS messages has also been developed. The intent here is to provide system users with a back-up communicatio

4、n mechanism in case of a network failure.Keywords:PLC TCP/IP GSM Remote monitoring1. IntroductionThe recent growth of networks technology and specially the wide spread of the Internet have promoted the development of distributed measurement systems for a variety of industrial applications. These dis

5、tributed measurement systems can be used in the monitoring and control of various instruments in the network.A Programmable Logic Controller (PLC) is microprocessor-based control system that can be programmed to sense, activateand control industrial equipment and therefore incorporates anumber of in

6、put/output terminals for interfacing to an industrial process. A control program stored in the PLC memory determines the relationship between the inputs and outputs of the PLC. PLCs are intelligent automation stations that possess highly useful and desirable features such as: Robustness. High degree

7、 of scalability: modern PLC families have a widespectrum of CPU types that allows easy scalability in functionality and performance. Extensibility: the modular design of PLCs enables the extension with a wide range of digital and analog I/O modules. Also, various integrated technology modules are av

8、ailable for various application areas. Sophisticated communication capabilities: modern PLCs have communication ports that provide for centralized or distributed connectivity. Powerful development environment: modern PLC families come with a cross development environment that support different langu

9、ages for programmability, allows semigraphical hardware configuration and offer strong debugging mechanisms.Remote access to control and monitor various devices in an industrial setting is of value to engineers and automation facilities.Current implementations of remote PLC monitor and control use d

10、edicated PCs or web servers connected to the PLC.Fig.1 illustrates a common architecture used in industry. As shown, PLCs are connected to the network through a computer. The PLC system is usually interfaced to this computer using the serial Portor Profibus. These types of systems are disadvantaged

11、by the dedicated use of a PC to access the PLC system. The architecture also does not make use of the advents and strides made in areas such as telecommunications and web technology.In recent years and due to the ever increasing capabilities of PC computing and the influx of network protocols and st

12、andards, there has been a surge in the design and implementation of distributed measurement and control systems for industrial applications. Typically, these systems are based on the clientserver architecture while securing communication using the TCP/IP protocol. Modern PLCs come with embedded webs

13、ervers that provide open access to useful real time information and diagnostics that can be viewed via any standard web browser.This remote accessibility provides several advantages over more traditional solutions. For example, a problem can easily be diagnosed and perhaps fixed remotely; also engin

14、eers can have remote access to the PLC CPU configuration tools and hence allowing for remote upload/download and configurability via the intranet or internet.In this paper we will discuss the design and implementation of a networked platform for remote monitoring and control of PLCs. The platform is

15、 built around the Siemens S7 series of PLCs. These PLCs have an integrated communication processor that can beused to provide accessibility to the internet. The monitoring and control can be accomplished in a wired or wireless environment,via an intranet or internet hence providing for a complete so

16、lution for the remote monitoring and control of industrial processes. We will also discuss the utilization of the GSM network and the operation of a communication protocol that uses SMS messaging to communicate with the PLC stations and a Database Server integrated with the system.The paper is organ

17、ized as follows: in Section 2 we describe the overall system architecture; section three includes a discussion of the software aspects of the system. Sections 4 and 5 present the communications methodology followed in this project and thepaper is concluded in Section 6.2. System architectureThe prop

18、osed system architecture is illustrated in Fig. 2.The system consists of the following components: Simatic S7 200/300 PLC systems and Communication Processors (CPs). Each CP has an integrated communication interface (hardware and software) that allows the PLC to communicate in a LAN, WAN or via a GS

19、M network. Clients and administrator are connected to the process via the network (or wirelessly). Privileges can be set or reset by administrators to allow for or to limit the various clients options. A Database Server connected to the process via the network for data logging and event recording. A

20、 variety of network options including GSM-based accessibility.The PLC system Ethernet module is a communication processor for the S7 family used to connect the PLC to the network. An additional communication processor is used to allow communication between the PLC and the GSM modem over the serial p

21、ort (RS232).In the proposed implementation, the PLC system reports remotely the status of the process to the Database Server. The Database Server records the status of the PLC in time-based tables and performs any required data analysis. The system also receives and executes commands from administra

22、tors and clients to control the process. GSM connectivity is also implemented to allow users with different privileges to access the status of the mandatory functions of the PLC and allow them to control these functions. Ethernet and GSM connectivity of the PLCs is implemented using the CP343, and t

23、he CP340 communication processors.The System software was implemented mainly using Simatic Manager and Java. The Simatic Manager environment is used for communication with the PLC system. The proposed architecture allows for programming, reprogramming, and configuring the system remotely.The Java ap

24、plication is developed using the S7-APIs (S7-Application Programming Interfaces) to establish the communication between the Database Server and PLC station. For example, using these APIs, we can instantiate objects that will connect the Database Server to the PLC station by specifying the IP Address

25、 and the S7 address of the CPU contained in the PLC unit.The PLC is connected to the process sensors and actuatorsusing I/O modules.After the Java application running on the server side establishes the connection to PLC using the S7-APIs, it then uses the Java Database Connector Technology (JDBC) to

26、 store the retrieved data that reflects the status of various PLC parameters in the Database Tables. JDBC is a technology that allows Java to connect to Database servers. It contains the required Java libraries that include all the necessary methods required to connect to theDatabase Server and exec

27、ute SQL statements.The overall system allows users to set process values using the PLC. For example, users can set an output (actuate a motor) or change the value of a memory cell (memory bit, byte, word, flag,etc.). The system environment also provides for obtaining the readings of input values (se

28、nsors readings) as well as capturing the status of the PLC. A Chart plotter can be used to convert readings from the PLCs into charts. An error reporting mechanismthat provides administrators with useful diagnostic information is also included in the complete environment. System administrators can a

29、lso query the status of the process using the GSM network in the form of SMS messages. Finally, the proposed system architecture is scalable with the ability to monitor a complete network of PLCs spreading around the Intranet or Internet.3. System software architectureThe systems software used in th

30、is project is divided into three components: A database management system Application modules (data manipulation modules, PLC communication modules and GSM modem modules) A user interface.Fig. 3 depicts the systems software major components and the directions of communication between them. A descrip

31、tion of each component is provided in the following subsections.3.1. An overview of the database systemThe database was created using Oracle 9i.It consists of a set of interrelated tables.Fig. 4 illustrates the database schema used in this work. For the sake of brevity a brief description of each ta

32、ble is provided below: A Station table that contains the entire information associated with the PLC such as station IP address, station name, etc. A Pointers table that contains information about each Input,Output or, Memory that the system is using. Pointers represent addresses for Input, Output or

33、, Memory. A Pointers reading table used to store the values read from items pointed to by the various pointers. This table is similar to a log table that holds the various stations activities. An Admin tablecontains all the information on system users. A Rank attribute indicates the security level f

34、or each administrator, such as, Main Admin, Supervisor, and Trainee.Additional information include login name, password, a Hint attribute for password recovery, etc. A Client table contains all the information pertaining to each client that is using the system such as user identification,password an

35、d phone. Admin_PLC and Client_PLC tables used to set the corresponding admin or client to a specific station id, and pointer id.3.2. Application modulesThese modules are at the heart of the software components of the overall system. They manage the communication between the user interface and the DB

36、MS. They initiate the connection to the PLC system and contain the needed objects for GSM communication.The application modules consist of following three sub-modules: A data manipulation module: this module has several classes that are called from within the user interface (GUI) to perform various

37、data manipulation tasks within the databasesuch as: insert, update, and delete. For example, the insert class is responsible of inserting any new data received through the user interface. A PLC communication module: this module consists of three classes; they are used to perform tasks such as accept

38、ing stations ID from users, verifying that each station has apointer associated with it, establishing connection to the PLC station, etc. A GSM module: this module provides for the communication between the GSM modem and the communication ports. The java communication package is used. This package a

39、llows java to recognize both the serial and the parallel ports that are part of the system. It contains the necessary functions required to send and receive AT commands and SMS messages through the GSM modem.3.3. The user interfaceThe user interface used in this work allows users (administrators and

40、 clients) to access and manipulate the database tables and to issue basic control commands to the different PLC stations. For database manipulation the administrator depending on his/her rank can insert, update, or perform different queries.Administrators can also perform other activities using this

41、 GUI such as sending SMS massages to different clients and administrators. Depending on his or her rank, an administrator can enter the configuration area, and perform activities such as viewing admin logs, viewing help documents, viewing tutorialsof how to use the user interface as well as controll

42、ing some activities in the station.Fig. 5 shows one of the GUI screens of the system. The figure shows the different fields that correspond to the station table attributes. Users can enter various values pertaining to a particular station such as its IP address, its location, number of inputs and ma

43、ximum number of outputs. As shown on the left panel of the GUI interface, users have the ability to search, view,configure, and update the information of a particular station.Fig. 5 depicts a GUI screen for the Update command. Users may use this command to modify particular station information such

44、as its IP address, or location.Fig. 6 is a snap shot of the GUI where the user is embarking on a search task. In the shown search screen the user is searching for a PLC station by location. The response to his search request is shown in Fig. 7.4. Using TCP/IP to communicate with the PLCThe CP module

45、 is a communication processor for the S7 family that allows PLCs to connect to an Intranet or the Internet in any LAN setup. The module supports the following TCP/IP communication services: Secure FTP (File Transfer Protocol) and HTTP (Hyper Text Transfer Protocol) server login with user IDs and pas

46、sword Send E-mail messages with embedded PLC data to standard SMTP mail server FTP client services for file transfer to a remote server FTP server services for file transfer to/from an internal 8 MB flash memory file system by a remote FTP client HTTP server services for remote Internet browser acce

47、ss S7 series program instructions for Internet communication.In addition the module also has the following features: Communication based on TCP/IP and ISO standards Factory installed MAC address Peer-to-peer communication capabilities with other S7 devices Multiple (up to 8) connections Ethernet cli

48、ent or server configuration options Program instructions for initialization, reconfiguration, and data transfer.A PLC can be programmed locally or remotely to sense,activate and control industrial equipment and therefore,incorporates a number of input/output terminals that are used to interface the

49、PLC to the environment or process. Each input and output connection point on a PLC module has a unique address that identifies it. Using the TCP/IP protocol, the IP address of the PLC, command type and the address of the item (I/O point) that is referenced are all contained in the IP packet. The IP

50、address of the PLC is included in the header field. The payload field of the IP packet is allocated to carry various PLC related parameters and commands.Fig. 8shows the contents of the frames that are sent and received from the PLC system.The Memory Parameters field contains information, such as the

51、 address of the item to be monitored and/or controlled. This item can be any of the following: Input Output Memory area Data block.It also contains other parameters such as data type (Boolean,integer, etc.), bit or byte offsets and so on.The Command Type field contains any of the following commands:

52、 Set Value Get Value Get Status.The Status field of the frame returns the status of the addressed item. The value field contains the value of the addressed item.5. GSM accessibilityForeseeing the potential of GSM services for low volume data transmission and acquisition.we decided to incorporate the

53、se services in our system. The idea here is allow administrators and clients to access the PLC system via the GSM network if needed, and also to be able to retrieve vital status information through it. The Java communication package was used to allow for the communication between the GSM modem and t

54、he various ports of the PLCs and the server. For the GSM modem that is connected to the PLC, ladder diagrams are used to send ATA commands as strings to the modem. Similarlythe received SMS messages are read as strings. A messaging communication protocol that uses the public GSM services and is suit

55、able for this project was developed. The protocol uses various frames to communicate with the system.Fig. 9 depicts the format used forQuery frames.A brief description of the various fields included in the above frame is given below.Type of Frame (TOF): this is a 1 byte field. The user (administrato

56、r or customer) should know what type of frame he/she is sending. For the query frame, the“Type of Frame”field should be set to the value 1.C/A (Customer/Administrator): this field indicates whether the user is a customer by writing“c”or an administrator by writing “a”. This field has a size of 1 byt

57、e.User ID: this field contains an ID for each user. The length of the field is 4 bytes.Password: this field indicates whether the password belongs to an administrator or a client. Administrators have full accessibility to change sensors status by using thesetfunction, for example.The maximum length

58、of this field will be 10 bytes which means the password cant exceed 10 characters.Station ID: this field contains the Station ID number. In this work, station IDs are assumed to be in the range of 1 to 9999.The length of this field is 4 bytes.Pointer ID: this field has the pointer ID number. The poi

59、nters IDs will be in the range of 1 to 9999. The length of this field is 4 bytes.The Query response frame: the response frame will be sent from the Database to the administrator or client with the status of a specific sensor. A frame illustration is shown inFig. 10.The Station ID and Pointer ID have

60、 the same meaning as described above. The Value field contains the returned value of the item whose status is interrogated in the Query frame.Note that the first 8 bytes in the response frame are used to store the following string:“The Query Results for PLC/Pointer Reading is”.Fig. 11shows an SMS re

61、sponse to a query.The query error frame: this frame will be sent to the Administrator or the customer via the GSM network to indicate that an error has occurred. This error can be either in specifying the password, for example, or the Station ID doesnt exist, or thePointer ID doesnt exist. The Error

62、 frame format is given in Fig. 12.The first 8 bytes are used to store the string:“Error:”. The Type of Error field will state or clarify the origin of the error, for example, a command type is not correct, or the PLC ID does not exist.Command frame: the command frame can be sent from the administrat

63、or to the Database Server or PLC seeking to change the status of a specific pointer using a“set function”. The different frame fields are shown in Fig. 13.A brief description of each field is provided below.TOF (Type of Frame): For the command frame, the Type of Frame field is set to the value 2.Val

64、ue: this field will contain the value that the administrator wants to set the specific addressed item to. For example, the Boolean which is used to set inputs and outputs sensors will have the value of 0 (false) and 1 (true).The rest of the fields carry the same meaning as discussed previously.Fig.

65、14 is snap shot of a mobile screen containing a command in the form of an SMS message using the frame format discussed above.6. Enhancing the security aspectsSecurity is critical to the remote access of industrial automation networks, as emphasized in recent articles in the industrial informatics field12,13. The introduction of internet-based accessibility within the process controls indu