Review of PLC's 2005 Development Trend

I. INTRODUCTION For a long time, PLC has always been the main battlefield in the field of industrial automation control, providing a very reliable control application for a variety of automated control equipment. The main reason is that it can provide safe and reliable and relatively complete solutions for automation control applications, which is suitable for the current industrial enterprises' needs for automation. On the other hand, PLC must also rely on other new technologies to face the impact of the shrinking market share, especially the impact of industrial PCs. The problem that PLC needs to solve is still the adoption of new technology, system openness and price.
The final trend of PLC technology exhibition is still one of the focuses of people's debate. Most people think that PLC will continue to lose market share; what is even worse is that in the face of industrial PCs, PLC will go to death step by step; but some people believe that some special industrial applications will still provide certain market share.
In the field of global industrial computer control, great changes have taken place around open and re-open process control systems, open process control software, and open data communication protocols. PLCs are almost everywhere, but this trend may not continue. With the birth and further improvement and development of SoftPLC control configuration software technology, the market share with SoftPLC configuration software and industrial PC control system is gradually increasing. These facts make the traditional PLC suppliers ideologically Dramatic changes have taken place. They must face reality and make a more open and high profile in the development and improvement of traditional PLC technology. For the control software, this is the core of the PLC controller. The PLC supplier is providing open-end programming configuration tool software to industrial users, and it is very active for industrial users. In addition, open communication network technology has also been a breakthrough, the result is to integrate PLC into a more open industrial control industry.
Second, open and based on industrial PC control
PLC manufacturers have begun to watch the impact of industrial PC-based control technology. Some experts even believe that the new technology and open technical specifications brought by the new business activities will bury traditional PLCs. PLC manufacturers believe that although there are a large number of PLC control devices installed on the industrial site, they still need to work with industrial control software companies in order to develop their own industrial PC-based process control software.
It is true that several years ago there was a clear mixture of old and new PLCs in industrial sites. Industrial users had to learn new and old knowledge at the same time, and even learn from each other. Most PLC manufacturers provide only soft logic and an operating platform for industrial users.
In the high-end applications, it is difficult to further distinguish between the PLC control system and the industrial PC control system, because both use the same type of microprocessor and memory chip. Imagery metaphorically, if you forget the literal meanings of industrial PCs and PLCs, then what you can observe in the box is just some basic computer hardware technology. What we observe more is the complexity of those basic technologies. Chemicals and hybrids, these technologies are effectively combined into the control system.
In addition, the reason for adopting open control is the need for system function integration on the one hand, and on the other hand due to the over demanding function of some industrial users. If you can give a high degree of attention, you can get more basic technical knowledge. PLC manufacturers focus on system functionality while industrial users focus on system applications. People can see that the future development trend is to further integrate more functions into a control box. Therefore, events such as sequence control and process control will be handled in a functional manner. Others such as motion control can also be shared in the same control structure system.
It is believed that PLC technology will continue to shift toward open control systems, especially industrial PC-based control systems. The latter in addition to the flexibility in the traditional PLC has a distinctly different advantages, but also has other advantages, such as can shorten the system into the market cycle, reduce system investment costs, improve the efficiency of the data flow from the bottom of the factory to the office automation Wait.
The problem of real-time response to industrial PC control systems has been well resolved. Perhaps the main thing is still hidden behind the technology, but it lacks corresponding tracking records. For PLCs, sturdiness is one of its main features, and there are already quite a number of tracking records to verify. Industrial users still treat the PLC with great care, and they are doing different technical tests on the PLC. When using a new technology, the question that industrial users need to consider is how much risk they have to take, and at the same time it needs to consider how many opportunities and benefits they can bring to their business activities.
However, industrial users do not fully believe the benefits of open control systems. With the further development of technology, they began to dilute these ideas. Industrial users are balancing the risks of adopting new technologies and the benefits of their business activities in order to provide effective protection for future decisions.
Industrial PC technology offers many features that enhance the PLC's features, including built-in video and high-speed floating-point digital coprocessors. Although Microsoft has no plans to further enhance this feature, the new Windows CE 3.0 is fully able to better meet the needs of process control.
Not long ago, Siemens announced a new set of software products based on open control systems, namely version 3.0 of SIMATIC WinAC (Windows Automation Center). WinAC is a control system solution based on Windows NT that is compatible with SIMATIC S7 PLCs and suitable for industrial PCs. WinAC 3.0 offers the connectivity of Profibus fieldbus LANs with higher integration and remote programming. In addition, it provides a new DeviceNet I/O device driver for localized integration of field control devices for connecting to installed DeviceNet I/O devices.
Steeplechase Software has also introduced an embedded Windows NT operating system interface component that supports hard real-time process control. This component further integrates hard real-time control software from Steeplechase's Industrial Compact PCI with SBS technology running in the Windows NT environment. Steeplechase's visual logic controller has now been upgraded to version 5.0. The controller is suitable for Windows NT 4.0 and Windows 2000 operating systems, its real-time engine can be directly integrated with the ordinary Ethernet and TCP/IP. The 5.0 version of the controller utilizes an enhanced OPC server driver and therefore runs faster than previous versions. Other features include new OI network features and the ability to allow industrial users to design rich and colorful dynamic graphics.
Transysoft recently introduced a new version of the ISaGRAF series industrial control configuration package, ISaGRAF PRO, which is a soft logic automation control package based on the IEC 61131-3 international standard and independent of any hardware platform. In a networked process control system environment, the software package can be applied to the development of a variety of configuration and distributed control systems. It contains a set of development tools, application work platforms, and corresponding "virtual machine" runtimes. aims. This runtime target can run on a variety of hardware platforms.
CTC Automation Engineering has released a new set of control software, MachineLogic PCLC (Industrial PC Logic Controller), which allows industrial PCs to play the role of PLC and still maintain the functional characteristics of industrial PCs. The software can complete the control tasks determined by a PLC and is as fast as the program execution time, all within 1 ms. It can also handle multi-task work at the same time, but it cannot exceed 16 control tasks at the same time. A mechanism with a prioritized and multitasking kernel keeps track of each control task, ensuring that control tasks get the highest priority. The software can run all five IEC 61131-3 standard programming languages ​​and PID control programs, supporting two types of I/O control devices. One is fieldbus I/O devices like Profibus and DeviceNet; the other is industrial PC I/O modules like ISA and PC/104. In addition, the software also provides online editing configuration functions for the control system. The program can be developed and run under Windows 95/98 and Windows NT, but it can also be executed under RTXDOS.
SoftPLC also provides Tealware, an industrial control software product that has been vividly described as a PLC wearing an industrial PC suit. The control systems installed on the rack already have the form factor of a small PLC, but SoftPLC's control software has been embedded in the CPU. Tealware software can meet the needs of various types of industrial users, from small, stand-alone systems to large, distributed multi-control workstation applications. Features include a full range of I/O modules, built-in Ethernet, and industrial serial communication interfaces.
Recently, Tealware software has been upgraded to version 2.3. Among them, the control software provides a virtually infinite ladder logic control step, allowing more than one million words of data tables; many OI/SCADA application interfaces; built-in Java engine and FTP server for remote maintenance and management; support User-written C, C++, Java programs, and device drivers; suitable for embedded Web servers; online operation of program design; robust I/O module support capabilities and many other standard PLC functions; Or, the converted AB company's PLC-5, PLC-2/PLC, PLC-3 and SLC-500 programs.
Third, the expansion of Ethernet and further accommodate Web technology
Currently, one of the biggest trends in all process control areas is the expansion of Ethernet technology. The PLC is an exception. Now, more and more PLC suppliers are beginning to provide Ethernet interface components. In the last few years, we have seen that it is a trend to develop a PLC that is more powerful than the existing ordinary XiaoLing PLC. Will Ethernet be the communication standard for PLC? Perhaps the end result is this, but it is still too early. There is a common misconception that providing an Ethernet interface on a PLC will solve all communication problems. Ethernet only defines several layers of protocol standards at the bottom of the OSI reference model. If the upper layer protocols are incompatible with each other, it is still impossible to communicate with each other. For example, this is just like a conversation between a Chinese who does not understand English and an American who does not understand Chinese is not able to make a phone conversation. Therefore, the protocol is the language that the devices communicate with each other.
On the other hand, the pace of progress has already been taken. We only have to face difficulties. In order to apply Ethernet technology to plant floor process control equipment, the ODVA Association has established a set of global standard technical specifications. Ethernet/IP standards to be able to solve the difficulties encountered in the actual work.
One of the things that is close to Ethernet is to be able to connect anywhere you want via the Internet. In fact, in some unexpected places, Web servers are showing their power. A few years ago, some PLC systems had built-in Web servers, which undoubtedly added more features to the PLC system. Other types of control devices are also preparing for further integration with Web servers. For example, Square D Company already has an engine control center with an Ethernet connection interface and is preparing to develop a transmission device with a Web server connection interface.
Benefits of having a built-in Web server body include open networks, business tools, and client/server relationships. In the past, industrial users may have typically asked for some information about PLCs, but now, due to the constant birth and development of new technologies, it is easy for industrial users to get information about this. On the other hand, with the large-scale production of chips and processors, PLC manufacturers can produce and provide open-network products, allowing industrial users to purchase PLC products with excellent functions at a small cost.
Schneider has become one of the pioneers in providing technical support for connecting PLCs to Ethernet and the Web. Recently, the company introduced a new fast Ethernet (100 Mb/s) module that runs on the Premium PLC platform. This module provides a full-duplex auto-sensing 10/100 Mb/s connection speed for PLCs that can connect to TCP/IP. The live process controllers can share real-time data information and automatically scan Momentum I/O modules. Any other field control device based on the Modbus communication protocol uses an embedded Web server to provide HTML communication services while providing SNMP for standard network communication management. At an exhibition, Schneider also showed industrial users their concept of a transparent factory.
In addition, Schneider recently introduced adapters based on Modicon's Momentum MIE family of processors that provide standard IEC program control capabilities, further providing a perfect solution for e-manufacturing. The adapter also provides the ability to connect intelligent I/O systems and other on-site process control devices to the Internet and Ethernet. On-site process control devices include all functional real-time process controllers.
A few years ago, Rockwell Automation also provided Ethernet interfaces in its PLC products and was steadily steadily improving the features of the Ethernet. The company has recently announced a flexible I/O module solution that uses non-patented versions of Ethernet technology to provide real-time process control performance. Type 1756 ControlLogix I/O from AB is also a component based on the standard Ethernet TCP/IP and UDP data transfer protocols. The application layer uses an open, object-oriented, producer/consumer-based technology. This technology can also be found in the ControlNet, DeviceNet and FF fieldbus H1 network systems.
Similarly, many other companies have also introduced Ethernet communication interface modules. For example, the communication interface provided by IDEC's OpenNet PLC controller enables compatibility with fieldbus devices such as DeviceNet, LonWorks, and Interbus. The controller utilizes an Interbus remote I/O master card that can handle no more than 480 local I/Os and 512 remote digital I/Os.
The 8051 industrial communications bridge provided by Sierra provides a good integration of PLC, DCS, RTU and SCADA systems that are incompatible with each other. This industrial communication bridge enables high-speed network applications over RS-232, 422, 485, or Ethernet communication links. The bridge controller provides eight RS-232 serial communication interfaces, two RS-485/422 isolated serial communication interfaces, two 10Base-T Ethernet interfaces, and one connection for redundant hot standby bridges Device.
The multi-vendor interface kit from ProSoft provides serial communication capabilities for AB's PLC, SLC, ControlLogix, and FLEX I/O (including the 1771, 1746, 1765, and 1794) platforms. Each module contains an 80386 processor and is embedded with a DOS operating system. Therefore, it can be considered as an industrial PC with I/O capability. In addition, the controller also has an "A>" disk operation prompt. , as well as the Autoexec.bat and Config.sys files. Applications can range from simple ASCII communications to sophisticated 32-bit control algorithms.
Another company, Giddings & Lewis, who is usually involved in motion control research, has also added Ethernet TCP/IP interfaces to its line of motion control products for the PiC (Programmable Industrial Control) and MMC (Mechanical and Motion Control) series. These unit components provide the ability to connect to the factory's internal Intranet and the Internet, allowing data information to be shared between on-site process controllers. Between on-site process controllers and industrial PCs, OPC server device drivers are usually used to connect real-time data information, and Ethernet network systems and Web technologies can be used for remote file transfer, program design, and system maintenance.
Nowadays, more and more companies are planning to gradually connect all their automation control devices to enterprise-wide information systems. For industrial users, perhaps they have noticed the Ethernet for Control series of control solutions, the technology is more dependent on Ethernet and the Internet. Almost all PLC vendors provide Ethernet connectivity in some of their serialized products, and some companies have already decided to completely embed Web servers inside their devices in order to fully demonstrate the performance characteristics of the PLC. Utilizing the Web connection feature of PLC, industrial users can not only monitor the operation status of the control system from anywhere, but also obtain any required data information just like the system manual.
Of course, if industrial users are starting to connect their control systems to the Internet, a secure information release address must be set up for this purpose. In addition, in order to prevent hackers from entering the control system, a set of firewall software with good security performance must also be installed.
SoftPLC has invested a great deal of enthusiasm and interest in network security. They have embedded a real-time and deterministic Java virtual machine into the process controller. Java makes it possible not only to run Web-based Active X control objects, but also to run Servlets. Servlets are highly integrated Web server tasks that provide dynamic Web page content. Servlets program code is clearly visible, object-oriented design, modularization, development is very simple and clear, Servlets also provide data information security performance, allowing further restrictions on real-time data information, such as only selected industrial users, or selected Registered data information. If the process controller is effectively connected to the Internet, then security is very important to it.
Hacking is not the only annoyance. If the network system is paralyzed, what do we need to do first? Hacking solutions use redundancy. Redundant IP addresses, redundant network systems, redundant communication cables, and hot backups are used in the process controller to provide good service for the process control system when an emergency occurs.
Many PLC suppliers continue to improve and improve communication performance during the development of their products. Their development direction is mainly oriented to Ethernet technology and Web-based technology.
Omron provides full Ethernet connectivity in its products. With its TCP/IP data transfer protocol, its products are fully compatible with all Ethernet specifications. In addition, the company recently released several new products based on Profibus-DP. The CS1 controller platform provides the operating characteristics of the main unit components to allow all process controller devices on the Profibus-DP network to run on the production platform; a new set of Sycon-DP configuration tool packages is also provided. Allows industrial users to easily configure the process control system and delegate the management of the network; in addition, a new multi-I/O terminal can be used as a Profibus-DP slave unit, which provides an interface for communication units. For connecting one or more I/O module units, there are Ethernet specifications. In addition, the company recently released several new products based on Profibus-DP. The CS1 controller platform provides the operating characteristics of all process controller devices on the Profibus-DP network that the master unit components allow to establish on the platform; it also provides a new set of Sycon-DP configuration tool packages. Allows industrial users to easily configure the process control system and delegate the management of the network; in addition, a new multi-I/O terminal can be used as a Profibus-DP slave unit, which provides an interface for communication units. Connecting one or more I/O module units works well with the company's C200H series PLCs.
Rockwell Automation also actively adds support for Ethernet connectivity in its products, including the Ethernet/IP, FLEX I/O, MicroLogix, and PanelView family of products specifically for ControlLogix. Similar products include ProcessLogix, PLC, and SLC 500 process controller families. Through further improvement and improvement, its products can simultaneously support the transmission of both implicit and explicit data information. With the help of implicit data information transmission methods, its data fields only contain real-time I/O data information.
The ControlLogix Ethernet/IP lineup includes an Ethernet/IP bridge module, an Ethernet/IP communication interface module, RSLinx software packages, and an Ethernet/IP communications interface transceiver. The FLEX I/O network interface module is suitable for Ethernet/IP, including a 10/100 Mb/s Ethernet/IP, including a 10/100 Mb/s Ethernet/IP fiber adapter. For MicroLogix, CompactLogix, SLC500 process controllers and other process control devices utilizing the DF1 protocol, the 1761-NET ENI Ethernet interface is supported for explicit data information transfer.
Automationdirect.com has introduced a new Ethernet Remote Master Module (H2-ERM) for its D2-240 and D2-250 PLCs. This new module connects the local CPU base unit to the remote slave I/O subsystem via a high speed Ethernet link. Each module can support 16 additional DL205 module units, 16 terminator I/O subsystems, 4 fully extended DL405 subsystems, or a mixture of any of these three types. Subsystems connected using Category 5 UTP cables must not exceed 100m between them. Repeaters can be used to extend the transmission distance and the number of nodes. If optical fiber transmission media is used, the distance can reach 2000m.
Advantech recently introduced the WebLink 2040/SDA product, which embeds Web server software that allows any machine, process controller, and smart sensor to be connected to the Internet or Intranet with Web-based HMI-SCADA software. The product also allows industrial users to securely access real-time data information from anywhere in the world via the Internet to monitor and control any on-site process equipment or system. In addition, through the company's Advantech Studio suite of software, industrial users can convert real-time, live graphics, trend records, alarm logs, reports, and recipes to a standard browser, anytime, anywhere.
Another type of Web server module from Newport Inc. is iServer, which makes it possible to connect existing PLCs and other control devices to the Internet. This DIN rack-mounted modular unit allows no more than 32 control devices with serial communication interfaces to connect to Ethernet and the Internet, acting as a Web server and an RS-232, 422, 485-compatible Ethernet serial bridge.
However, not all PLC communication performance improvements are for Ethernet or Internet. Not long ago, Rockwell Automation announced a new version for ControlNet and applies to AB's PLC-5C field controllers and SLC 500 adapter modules. The deterministic and nondeterministic network connectivity features provided by the 1747-ACN15 and 1747-ACNR15 adapter modules for SLC (1746) I/O are now fully compatible with their PLC-5C field controllers.
Moeller Electronics previously used a proprietary communications protocol and has now begun to move toward open network protocols. Their new generation of I/O structure called XI/ON will become an integral part of its PLC development. With this architecture, fragment and modular design work is possible. The integrated gateway allows connection to Ethernet, Profibus-DP, DeviceNet, CANOpen, and more network systems.
The enhancement of PLC-related communication performance is not only reflected in hardware but also fully reflected in software. For example, KEPware Corp. has introduced a new generation of 32-bit Control-Logix Ethernet OPC server drivers for its KEPserverEX family of products. The OPC driver software improves the speed and connectivity between OPC and DDE customers and AB's ControlLogix field controllers; it also provides a flexible human-machine interface; you can freely use AB's OPC server suite. It also includes the PLC5/SLC505 Ethernet driver. It also further optimized the 1756's ENET interface, improved communication performance, and supported the company's automated identifier database.
Fourth, process control applications
Although traditional PLCs have been applied in the field of discrete process control, PLCs have been widely used in the field of continuous process control, and the development trend based on continuous process control technology is further growing. Communication is a key technology for PLC applications. This technology has been expanded in the PLC field. As with systems, decentralized processing of PLCs has become possible, so it is easier to manage them so that they can be better integrated.
Facing the enormous competitive pressures existing in the traditional industrial process control market, many PLC suppliers are beginning to actively transfer the process control applications they serve, and must abandon some of the market share that traditional PLC applications already occupy.
After a short period of hard work, Siemens rolled out its PLC products based on process control, introduced SIMATIC PCS products before 1990, and upgraded their products to PCS in 1997. This development work has continued We are satisfied with Siemens, but with the constant birth and development of various new technologies, the development work will not stop. Although both discrete and continuous process control applications use the same hardware products and network systems, additional special modules may be needed, but there are always some differences between them. As long as different types of application software are loaded into the same system, different process control applications can be completed.
Any PLC supplier will continue to concentrate on the research and development of batch and hybrid process control. As a good example, Schneider Automation just brought us its QPC (Quantum Process Control) product, which enables a control system to be truly fully targeted in the field of process control. QPC uses a networked distributed PLC system to complete process control applications. Based entirely on Quantum PLCs and Momentum I/O operating platforms, QPC can scale from a single Quantum PLC to a distributed system and can also be fully integrated with Ethernet, Internet, and TCP/IP technologies.
Rockwell Automation plans to further enhance the process control performance of AB's ControlLogix multifunction controller while adding a redundant set of solutions and flow meter modules. Its 1756-CFM configurable flow meter module will provide the ability to support two channel 0-120 kHz frequency inputs and accept input signals from most turbine or mass flow meters. In version 6.0 of RSLogix 5000, both the function block diagram (FBD) and the process control instruction table will be provided. Its ControlLogix platform also integrates RSView's visual HMI software components. In ControlLogix, ActiveX panel display controls work with process control instruction tables and provide the perfect picture display for process control applications based on RSView. In addition, its RS series batch control applications also provide integrated S88 batch processing capabilities.
Toshiba Corporation has released its V-Series integrated process controller that can further integrate PLC systems, DCS, and work to control computers. Its main features include: providing a common set of configuration engineer toolkits for all three operating platform modes; providing a common backplane bus architecture for any combination of sequence controllers, loop controllers, and computer modules; Provides a common identifier database for global process variables and Windows NT 4.0; also provides a common set of Ethernet-based LAN network systems. The controller programming language is compatible with the IEC 61131-3 standard. Its Web connectivity capabilities help industrial users remotely configure, find and repair faults and other engineering activities.
The Siemens PLS 7 process control system was originally based on the SIMATIC S7-400 PLC and has recently been upgraded to version 5.0. One of its greatest features is a flexible distributed server/multi-client architecture that perfectly combines open bus architectures. Communication protocols based on Profibus and HART fieldbus are widely used for field control device integration; Profibus fieldbus, industrial Ethernet, TCP/IP are used for system bus; Ethernet TCP/IP and Fast Ethernet are used for terminal bus and enterprise integration Connection.
Similarly, Rockwell Automation has also introduced an enhanced ProcessLogix decentralized control system. Subsequently, it announced its FlexLogix decentralized control system, which contains the 5430 FlexLogix controller and existing Flex I/O control equipment products. The Model 5430 controller and AB's ControlLogix multifunction controller use the same process control software package RSLogix 5000 as Rockwell Automation.
Rockwell Automation's ControlLogix 5550 multifunction controller has added 3 new instructions to meet the needs of motion control, and has also added two new coordinate types. By allowing RSLinx software to receive all identifier data lists with a single request command, network data throughput is greatly improved. In addition, the OI tool now has a graphical interface that allows for the monitoring of trend chart and histogram values, adding a system browsing tool.
In the PPC-2000 hybrid temperature controller introduced by Watlow Anafaze, multi-loop PID control function and programmable logic control function are integrated in the same process control software package, with 48 PID loops and 48 digital I /O point ability.
Moore introduced the Internet-based control system, Procidia, specifically designed for process control. The system is controlled by Internet technology, Procidia. The system uses local and remote operations and controls through the Internet and intranets of an enterprise, using self-configuration methods based on industrial PCs HMI and OPC server.
VMIC brought the industrial PC-based controller VMIPC-8400, which also embeds the corresponding IOWorks process control software package. The VMIPC-8400 complies with the IEC 61131-3 international standard and is ideally suited to the needs of continuous process control and PLC applications.
V. Redundancy features
In the field of industrial process control, the demand for products with higher reliability systems has been increasing year by year, the vast majority of which are driven by economic interests. The cost of a factory downtime loss is extremely expensive, and the resulting production costs increase. Especially in Europe, the main body of a series of rules and regulations is gradually being improved and strengthened. The IEC 61508 standard now published provides a design basis for the safety performance of the process control system, which is mainly formulated for the functional safety design within programmable electronic systems.
PLC has been used for a long time in the field of safety shutdown system. Perhaps Triconex and Pilz can provide us with many insights about this application, but other PLC suppliers are also looking at the prospects of this application area, but also make some PLC hardware suppliers feel very tricky. SoftPLC has introduced a solution for a redundant system to meet this application requirement and has also been applied in practical projects. Its application experience tells us that the main secret lies in the careful selection of hardware and unique I/O structure, and they also find some bus systems suitable for the application in this field and other unmatched things.
Other well-known PLC suppliers have recently provided corresponding products for safety and redundancy applications. Rockwell Automation has just launched the Guard PLC 1200 and 2000 series of safe process controllers and, along with its existing PLC system, provides monitoring and regulating safety operations for all automation systems. The process controller contains a redundant CPU system and uses internal test circuitry to check the operation of the I/O modules instead of directly using redundant I/O modules. The system complies with the IEC 61508 standard safety technology specification and is also accredited by the TuV product service organization. It can be fully applied to automated process control applications with SIL 3 safety level requirements.
Rockwell Automation also adds redundancy options to industrial users in its ControlLogix platform. A new software component is suitable for the 1757-SRM system redundancy module in order to make the appropriate choice. It can use RSLogix 5000 programming software to form a redundant system with other modules and use standard components such as power supplies, chassis, and ControlNet bridges.
Schneider Automation offers industrial customers a choice of Quantum family hot backup solutions for critical applications. When similar data information passes through the Quantum family of remote I/O processors, the host processor and data information it connects to needs to pass back and forth between the check link and the processor itself. The hot standby processor can monitor the addresses of the Modbus TCP/IP, Modbus+, and Modbus communication interfaces, so the control transmitter for client computer communications is explicitly transmitted.
Triconex recently announced a series of new products. Including a new version of the Trident triple modular redundancy controller that can be used in small application systems up to 450 measuring points, its features include an analog output module, a pulse input module and an enhanced communication function In addition to modules, it also includes off-the-shelf analog inputs, digital inputs/outputs, and solid state relay output modules. In addition, the controller is also fully compatible with the OPC connection specification, at the same time it is certified by the Tuv Rheinland organization and meets the SIL 3 safety level requirements, and also complies with the DIN AK 6 level installation specification.
Triconex also introduced a new version of TRICON 2003 PLC. Its main feature is that the digital processor is more than twice as fast as the original version.与以前的版本相比,TRICON 2003 PLC同样兼容OPC连接技术规范。
Siemens公司已经开始积极主动介入这一应领域,并及时推出了SIMATIC S7-400F产品。该产品属于其高端S7-400 PLC的一个具有自动保安装置的版本,主要目的是为安全停机系统应用而设计的。它能够满足IEC61508标准所制定SIL 3安全等级的运行要求。如果有临界应用情形发生,控制器能够进入到用户定义的安全状态,以便按照预定的顺序执行停机程序,随后就可以向工业用 户提供诊断数据信息报告。系统程序由SIMATIC STEP 7通用开发环境来完成,该开发环境为工业用户提供了程序模块库和安全功能模块。
GE Fanuc公司去年就已经推出了型号为Max-ON的热备份冗余软件,该软件被应用于标准系列90-30 PLC系统,通过Genius LAN通信网络,远程I/O彼此之间可以进行通信。软件由即插即用型子程序组成,以便进一步完成诸如变量同步、冗余I/O总线控制、程序等价测试、主CPU的挑选以及高级诊断等一系列任务。
六、运动控制
PLC在运动控制领域的应用也已经有很长一段时间了,而且还保持了很好的增长趋势。
最近,Automationdirect.com公司计划为其DL205 PLC推出具有四通道高速计数器的H2-CTRIO模件。该模件单元支持4个独立可组态的100kHz计数器/定时器通道,还具备4个隔离高速DC输出通道,并运行于独立的CPU扫描程序,使其具备了非常快速的响应能力。该模件也能够通过本地基于计数事件的处理器进行编程,而不需要从控制CPU中得到任何协助。程序设计通常采用DirectSoft32和Think & Do工控组态软件包来进行。
结合机械和运动控制方面的内容,Giddings & Lewis公司提供了基于工业PC的MMC(机械与运动控制)软件产品PiCPro for Windows,该软件兼容于IEC 61131-3标准的梯形逻辑图和功能模块图表程序设计方式。该软件内藏于PCI总线模件中,当宿主工业PC停机以后,该模件单元能够继续运行操作。其特点包括不超过32个轴向的模拟量控制或者SERCOS伺服系统控制,具备运动控制性能,内藏OPC服务器驱动程序、电子邮件和文件传输器,以及为DeviceNet或者Profibus提供的通信接口,另外还提供了标准Internet和Intranet访问工具。
七、软件工具
现在,软件工具继续成为PLC用户最感兴趣的内容之一。对于PLC硬件,工业用户只需要关心其性能和价格方面的内容即可。当前,越来越多的PLC用户希望能够寻找到更多的软件工具和集成工具,以便能够进一步提高PLC硬件的性能。
工业用户所有工作的目的在于实现系统集成,所以他们正在努力实现将运动软件包、PLC、操作员界面甚至Internet结合在一起。同时,工业用户还希望开放控制能够完成逻辑控制,也能够运行Java脚本程序。
然而,问题在于工业用户通常是通过购买PLC硬件产品的方式来免费获得软件工具的。如果工业用户打算支付软件费用,他们希望花同样的费用能够购买到与市场上质量相同的PC软件。软件供应商也正在努力开发,并希望能够为工业用户提供更多软件工具的选择机会。
Rockwell自动化公司提供了基于RSLogix系列版本的袖珍型软件RS-PocketLogix,该软件运行在基于Windows CE操作系统平台的袖珍型计算机上,用于工厂底层SLC-500和MicroLogix可编程控制器的维护和故障处理,支持PLC-5和所预定的ControlLogix逻辑控制程序。
现在,Rockwell自动化公司已经将软件升级到RSLogix 5000系列版本,该系列软件版本采用了ControlLogix结构体系和Logix 5550处理器。RSLogix系列版本软件其自身已经升级到4.0,此外,借助于对AI系列入口命令、改进的安全性能和有效性对比,以及一种新地址向导的支持,能够支持AB公司的PLC产品和个别改进程序。
Nematron公司也已经发布了5.40版本的工业自动化套装软件,该软件增加了在线逻辑控制变更、流程图表跟踪等功能,允许工业用户真实地跟踪逻辑控制路径,增强报表和编辑能力,包括标识符交叉搜索和所有报表打印等。为流程图表开发所增强的编辑功能包括全程搜索、标识符名称的替换、自适应流程图表模块,以及改进的剪切和粘贴性能,以便有能力将注释性内容嵌入到流程图表模块。新版本软件也增加了对OPC 2.0的支持能力,包括标识符浏览和数据信息访问等。
Siemens公司的SIMATIC STEP 7是一套全开放专业版软件,并已经成为该公司通用开发环境软件工具,直接用于组态、管理和维护工厂范围内的自动化控制系统。该软件使工业用户可以将一个自动化工程项目再细分成设计阶段、执行与测试、委托与启动、运行,以及维护等,然后,将所有工作集成在单个软件包内。单个自动化工程项目可以采用许多程序设计语言的任何组合来进行编程工作,从而在其中选择最适合于所给定应用程序的那一部分。同样的程序代码能够在基于工业PC的SIMATIC WinAC控制系统中得到运行,以满足软件和硬件对实时性的要求。
不久以前,新合并成立的Entivity公司已经发布了Think & Do Live软件。该软件是一套基于e-控制方案的产品,并集成了控制、通信和信息技术,同时也是一套能够提高生产效率的现代化软件工具。该软件所内藏的机械和过程监控功能能够与可操作的信息显示结合起来,以便进一步提高生产效率。该软件还能够被应用作为综合控制、通信和监控系统的解决方案,或者应用于遗传算法控制系统。
同样,Automationdirect.com公司也推出了新版本的基于工业PC的过程控制软件包,现在,该软件包包括了全套OPC 2.0兼容服务器,以及对RUNtime PC和WinPLC的完全性支持能力。
Schneider公司推出其Modsoft系列产品的新一代软件ProWORX Nxt,该软件为Quanturn、 Compact和Momentum PLC等流行硬件产品平台提供了基于Windows操作系统的图形化用户界面,也提供了与984系列产品兼容的梯形图逻辑编辑器,为编程面板和PLC之间提供了直接或者网络方式协同工作的连接选择。另外,它还支持Modbus、Modbus+和依靠Ethernet TCP/IP协议的局域网连接方式。其他特点包括组态环境中的最新型图形化用户界面、改进型文档,以及支持所有梯形图和文档之间转换的实用程序。
最近,Giddings & Lewis公司为工业用户提供了一套集成了IEC 61131-3标准逻辑和运动控制编程环境的软件产品,即PiCPro for Windows。该软件产品将所有特点集成在一个工程项目管理器之中,可以在线开发用户帮助信息,还可以通过Internet进行程序设计,同时支持SERCOS系列运动控制产品。
自从所有编程方式被软件工具替代以来,PLC编程软件已经发生了根本性的变化,而且这些软件工具仍然保持着一定的增长趋势,并且不断有适合于各种应用的新特点诞生。
Siemens公司推出的3.2版本STEP 7-Micro/Win 32程序设计软件提供了一种新的FBD编辑器,以及与IEC 61131-3标准兼容的梯形图程序设计语言和FBD。该软件能紧密地与Windows操作系统集成在一丰收,提供诸如增加/移动程序和定制安装方式等一系列功能特性。同样,在Windows中采用单个工程项目文件的方式更加容易对工程项目进行管理,如电子邮件和备份等。另外它还提供了新的保存方式选择,只要双击工程项目文件就能够自动启动工程项目。
SoftPLC公司正好也发布了TOPDOC NexGen(被称为下一代)软件。TOPDOC是一个梯形图逻辑程序编辑器和用于SoftPLC开放结构体系控制软件与过程控制器的维护工具。该软件采用了Java程序设计语言进行开发,其主要特点是充分采用了Web技术,从一个Web浏览器上就可以进行远程监控和修改PLC参数,而且能够运行在Windows和非Windows操作系统平台上,如Linux。
Altersys公司和Indusoft公司进一步联合起来,分别推出了基于Altersys公司ISaGRAF系列的Virgo自动化套装软件,以及基于Indusoft公司的Web工作室。Virgo套装软件能够嵌入到Windows CE中,并通过Internet与其他过程控制系统建立起通信链路。借助于ISaGRAF系列产品和IEC 61131-3技术标准,Virgo套装软件包括了自动化过程控制系统(嵌入式或者非嵌入式)组态和运行所必需的软件部件,如HMI、报警、事件记录、趋势记录、硬实时控制和通信等。
另外一种来自于IPMI公司的基于Java技术开发的软件产品是EPS for Java,该软件重新开发了新版本的图形化继电器梯形逻辑组态编辑器。由于该软件基于Java程序设计语言,因此是一个交叉运行平台,相同的拷贝可以运行在Windows 95/98、Macintosh或者其他操作系统平台,并同时支持Java运行环境。
Entivity公司最近发布了版本号为6的Think & Do Studio软件产品。该软件产品是建立在Visio技术基础之上,并在一个标准开发环境中集成了流程图表控制逻辑、HMI、运动控制、PID回路控制、智能化I/O控制设备接口,以及工程项目文档工具。该软件可以完全升级并跨越Microsoft Windows平台,到目前为止,据说是第一套基于COTS软件平台的过程控制软件包。其最显著的特点之一就是所具有的自动查找和组态工具能够使其非常容易地连接到智能化I/O过程控制设备网络系统中去。
八、硬件与软件
通过短短几年的努力,我们不断看到有许多新的软逻辑控制软件产品被推出。许多独立软件供应商已经开始出售这种软件产品,传统PLC供应商在他们的产品目录中也已经开始逐渐增加基于工业PC的控制产品。另外,PLC开发费用中,软件开发费用所占的百分数正得到稳定的增长。例如,Rockwell公司将40%的开发费用投入到硬件产品开发中,而将60%左右的开发费用转移到了软件开发工作上。其着眼点在于全球市场对软件产品有强大的购买力,并要求软件产品能够更加完美地运行在工业标准平台上。
PLC一般总是使用梯形图逻辑控制程序,现在,所有类型的其他产品正在努力获得并使用一些或者全部与IEC 61131-3标准兼容的程序设计语言,包括梯形图逻辑图表、功能模块图表、顺序功能图表、结构化文本和指令表等程序设计语言。
然而,硬件、操作系统和应用软件相互之间都是延缓此独立的实体,与传统的全集成PLC系统有很大的不同。随着硬件和操作系统的不断发展,操作系统所提供的标准商业化功能特性可能会进一步促使PLC变成一种更加不同的控制设备,这也就是PLC需要采IEC61131-3标准程序设计语言的原因所在。
可以采取各种方式来解决PLC的编程问题。Rockwell公司对其所有产品均采用Logix系列软件来编程,包括机器人控制器、软逻辑控制器。传统PLC系统全部采用RSLogix 5000软件进行编程工作。其他途径包括微软技术,像DCOM、ActiveX以及Sun的Java等,在将来,也许会使用Microsoft.Net技术,其中大多数编程方式是通过Sun宏系统和ONE(开放网络环境)来发布的。
基于Windows CE的应用软件和标准工具将允许工业用户可以通过多重硬件生命周期的方式来保护他们所购买的软件。这种趋势将进一步改变工业用户对传统PLC产品产品的购买决心,而且仍然要涉及到PLC硬件技术规范、外围设备和通信连接能力,这好像有些类似于购买一台工业PC。相对于工为一用户习惯性决定过程而言,他们需要认真评价一种过程控制器及其编程软件的灵活性。这也有助于平息人们评价哪种程序设计语言是最好的争论。梯形图逻辑、流程图表、静态逻辑、功能模块、IEC 61131-3标准混合编程,连同Visual Basic和Visual C++等都能够很容易地把基于Windows CE的PLC作为一种对象来对待处理。不久以前,一些亲的软逻辑和基于工业PC控制的产品已经问世。
来自于制造业数据系统(MDS)公司的WinMotion软件在单个套装软件中提供了软运动控制、软逻辑控制(兼容IEC 61131-3标准)和一套数据服务器,并不需要任何运动控制接口卡件,或者专用硬件产品。此外,它还能以实时方式提供连续包括维护、生产和质量等数据信息。该软件可以运行在具有单个处理器并安装有VenturCom RTX软件部件的Windows NT操作系统平台上。该公司还公布了一套开放式API接口,能够让工业用户进步集成第三方软件技术。
Rockwell公司也推出了SoftLogix 5800软件。该软件提供了一种新的软控制器,在一个相同的控制系统中,能够同时完成顺序和运动控制功能。与该公司其他Logix产品一样,该软件仍然使用了Logix运行引擎,RSLogix 5000编程软件和NetLinx开放式网络。该软件也能运行在Windows NT/2000操作系统平台上。
前不久,Entivity公司推出了5.1版本的可视化逻辑控制器软件。其显著特点是增加了一个对DeviceNet标识符组态器的安装选项,以及改进的OPC服务器。该软件对NVRAM有更好的支持能力。
Automationdirect.com和KW公司联合推出了适合于WinPLC CPU模件运行引擎并兼容于IEC 61131-3标准的ProConOS PLC产品。它具有抢占式、多任务运行引擎,而且被嵌入到Win-PLC模件中。应用程序的开发采用MULTIPROG来完成,MULTIPROG是一套兼容IEC 61131-3标准的软件开发工具,它允许工业用户在WinPLC上同时运行任务,然后被独立地运行,而且可以具有不同的运行循环周期和时间版段。
Twin CAT软件系统公司所推出的Beckhoff软件可以运行在安装有Windows NT/2000或Windows CE的工业PC上,能够将I/O接口嵌入到实时过程控制器中,形成多PLC系统、NC轴向控制、程序设计环境和操作站。所显示出来的特点实际上是嵌入了IEC 61131-3软件的PLC,或者是工作于Window NT/2000操作系统平台下的软件NC。程序和运行系统可以在相同或者独立的工业PC上运行。用户界面和其他程序之间的数据信息通信则依靠Microsoft公司的开放式标准,如OPC、OCX、DLL等。
九、适合PLC应用的新模件
前文已讨论了新的适合于PLC的插入式运动控制模件。对于其他类型的插入式部件及其附件,可以获得更好的选择,同样还有一些较新的选择方案。
Siemens公司已经推出了一种新的基于AS-I现场总线标准通信处理器模件CP243-2,该模件为低级变送器总线提供了直接地址连接方式,还能够与任何S7-200 CPU及其扩展版本工作在一起。
Automnationdirect.com公司推出了一种名为EZText的新型PLC文本操作面板,该产品支持广泛通信协议驱动程序的选择。所支持的通信协议包括该公司的LOGIC、AB公司的DF1、Omron公司的Host Link、Mitsubishi公司的FX系列、Modicon公司的Modbus RTU和GE Fanuc公司的SNPX等。每个EZText操作面板都可以在DeviceNet版本中得到很好的利用。所有模伯均提供了5个用户可定义按钮、一个内藏菜单系统、滚动式数据信息输入,以及全隔离电源供应。EZText操作面板还提供了5个用户这下义的LED和LCD显示窗口,可支持2-4行不超过20个字符数据信息的显示。
Aromat公司为其FP0系列PLC提供了一种具有12位分辨力和8通道模拟量输入模件。一个FP0能够处理不超过24路的模拟量输入信号,还能够完成多种浮点数字运算、精确PID控制和自整定。只要通过调制解调器就能够进行模拟量信号的远程监控。
同样也来自于Aromat公司的一种新模件是FP2 PLC。FP2 PLC模件具有高速计数能力,依靠4个信号通道其最高频率可以达到200kHz;同时,一个活动的电动机动动单元能够处理4个方向的轴向运动,而且每个轴向运动的速度可以达到100kp/s。另外,它还具环回路控制或者PWM输出。
ABB自动化公司提出了一种新的称为Industrial IT的编程解决方案,并成为其AC 800F现场控制器产品的一部分。AC 800F所具有的开放结构单元体系能够同时处理本地和远程I/O模件、智能化传感器的4-20mA信号,是一种具备了多种现场总线技术的现场控制器。AC800F还提供了减少工程设备安装周期和资产优化分析等性能,通过OPC技术提高了与ActiveX和Web的连接能力。AC800F中的每个单元可以从4种独立的现场总线网络采集和处理各种诊断数据信息,它还提供了与IEC61131-3兼容的编程工具软件。
十、驾御现场设备级控制
随着通信技术的进一步发展,有可能利用通信系统将控制功能形成闭环过程控制,因为越来越多的控制计算机已经嵌入了I/O系统。
例如,Rockwell自动化公司所推出的DeviceLogix充分应用了模件技术,能够被完全集成到工厂底层现场过程控制设备中去,为现场设备级提供了低价格过程控制应用。DeviceLogix还提供了简单化独立过程控制应用特点和性能,诸如单个应用条件、事件侦测、报警管理和布尔逻辑运算等,减轻了具有较多控制任务的控制系统主控制器,甚至是最低级过程控制设备的负担。首先推出的过程控制产品是AB公司的1792/1792D系列、ArmorBlock MaXum I/O系列、1791D CompactBlock I/O系列、1799嵌入式I/O系列,以及800E DeviceNet局部操作站和DeviceNet辅助软起动器系列。
在2000年初,Siemens公司就推出了IM 151/CPU,同时将所增加的PLC功能应用到ET 200S I/O系列产品。
Festo公司也已经将PLC技术嵌入到其气调节阀产品中。该公司近推出的SB6产品在这一领域得到了很好的应用。另外,它提供了与AB公司SLC-500相同的技术特点,通过便携和远程等增加了数字量的模拟量I/O系列模件通道。SB6还提供了一个兼容于DeviceNet的电子式节点,能够与DeviceNet数据采集器集成在一起,百且介于电子模件和气动模件之间,为各种应用功能提供了PLC逻辑控制。
Phoenix Contact公司所推出的系列化DIN架装式PLC被称作远程现场控制器(RFC),而且非常适合于Interbus I/O系统的应用。所有模件单元都能够采用PCWORX组态工具软件进行编程设计工作,PCWORX是套完全基于IEC61131-3标准的组态工具软件包。
Wago公司所推出的可编程现场控制器能够完全与其Wago I/O系统工作在一起,允许工业用户在本地存储和运行程序,同时还能够与网络系统进行通信。它并不需要通过网络传输就能够对信号进行预处理和逻辑解决方案的调试。信号预处理从相当程度上降低了装载现场数据信息的负荷,能够为现场过程控制建立起非常完善的分散控制应用。
VMIC公司同样也推出了增强型版本的DIN架装式IOMax PC控制器,即VIOMAX-8450。现在该控制器已经采用了300MHz的MMX微处理器芯片,而且仍然采用基于IEC 61131-3标准的IOWorks控制组态工具软件包进行编程设计。
十一、替代嵌入式控制器
据相关调查报告显示,现在对于低端PLC市场的争夺仍在继续进行,这也进一步促进了PLC的发展。随着微型和超微型PLC技术的发展和数量的增长,它们已经开始进入到新的应用领域。例如,微型PLC已经开始替嵌入式控制器的工作内容。像Omron公司已经察觉到这一技术发展的新动向,并逐渐计划将其产品应用于商业器具、饮料分发设备以及商业、工业等。这些行业之所以正在应用微型PLC,正是由于它具有卓越的灵活性、市场开发周期短、适应性强、竞争性的价格等一系列优点所至。
对于PLC或者嵌入式控制器的选择主要依赖于它们的体积大小,尤其是如果需要特殊功能时,嵌入式控制器的缺陷就逐渐显露出来了。尽管嵌入式控制器具有很低的价格,但其中仍然包含了质量控制、维修以及服务等方面的价格。
Mitsubishi公司的FX1S超微型和FX1N微型PLC系列产品正在面向嵌入式应用领域发展,它们能够处理从10-128个I/O通道,并且具有2个轴向的运动控制性能,还具备PID控制指令应用于连续过程控制。
来自于Entertron公司的SK1600-RIC型嵌入式可编程逻辑控制器(ePLC)具有16通道数字量输入和12通道继电器输出基本单元、一个RS-232接口、一个10kHz高速计数器通道,以及4kb的程序存储器。另外,它可以在Windows和DOS操作系统平台下采用梯形逻辑图编程方式进行控制程序设计。该产品还能够被应用于有或者无操作员界面的连接。
Omron公司最新推出的CPM2B系列微型控制器,其设计仍然保留了工业用户所希望的低性能价格比的特点,以便工业用户能自由构建控制系统。其特点还包括提供了备份电池、增强型通信机制、I/O通道可扩展到128路、RS-232接口、可移动终端、PID控制回路以及其他高级指令系统等。
Blue Earth Research公司已经将Xplor-52R控制器增加到其为嵌入式控制应用所设计的Xplor系列个人数字控制器中,能够提供有限的监控功能和数据信息记录应用。它能够支持Xplor系列所有标准特点,同时包括了一个89C52 CPU单元和用于存储Basic程序的8kb的EEPROM存储器,以及一个RS-232接口。其他元件包括一个8通道12位A/D转换器、一个4通道12位具有有效输出电压范围的D/A转换器、一个看门狗定时器,以及一个LCD和键盘接口。
十二、PLC将会成为过程控制领域内的日用品
仅仅从PLC系统价格正在逐渐降低的理由进行推理,尤其在低端应用方面,PLC将会成为这一领域的日用品。由于PLC系统最小模件单元的价格也只不过100美元,甚至更低,即使这些模件出现故障,工业用户从心理上已经感觉不到是否还值得重新修理。许多工业用户直接采取了抛弃出现故障的模件,进而换上一块新模件的处理方式,因为重新修理这样的故障模件也许会花费同样甚至更多的费用。
相反,我们不要被低价格所愚弄。一些小型甚至超小型PLC系统已经向工业用户提供了模拟量I/O、PID控制回路、通信接口,甚至与企业网络系统相连接的现场总线。具有14个通道的I/O和4个PID控制回路的PLC系统,其价格才99美元,这种产品非常适合小系统控制应用的需要。
一些PLC供应商依托强大的应用市场继续发展小型PLC产品,甚至大量的工业用户已经将其看作是低端应用市场上的日用品。PLC供应商需要充分考虑的问题是他们不仅仅要供应硬件产品,还必须采取相应的措施为工业用户解决工程师可用的组态工具、故障诊断技术、网络通信能力以及除基本自动化硬件以外的附加软件包的适用性能。
Rockwell公司最近为其Compact Logix系列产品增加了一种新的Compact Logix 5330控制器。该控制器能够与1769系列Compact I/O模件,不超过256个本地I/O测点,另外还为用户提供了256kb存储内存。CompactLogix使用了相同的能同时被ControlLogix、Flex Logix、SoftLogix和RSLogix 5000共享的Logix控制引擎。
Automationdirect.com公司为其DL05型微型PLC也提供了个别新版本产品。D0-05DD-D包含了具备8通道DC输入和8通道DC输出的DL05 CPU模件,采用了12/24 V DC电源供电、具备6kb的存储器,可利用RLL/RLLPlus进行程序设计,还提供了一个RS-232程序和通信接口。它具有两种可组态并独立于CW/CCW的脉冲顺序输出或者步序,直接脉冲输出频率可以达到7kHz。此外,D0-05DR-D还提供了6通道继电器输出。
Siemens公司为其SIMATIC S7-200系列产品推出了采用一种新类型CPU的微型PLC系统。新类型CPU为S7-226,该CPU为能够进一步连接到工业LAN系统或者诸如调制解调器、打印机、条形码阅读器等外围设备,相应增加了点到点接口(PPI)或者自由接口(连续ASCII)。
来自于GE Fanuc自动化公司的一种新产品是VersaMax CPUE05 CPU模件。该模件的特点主要包括与Ethernet等的连接能力、更快的指令执行时间,以及更多的用户存储器支持。新增加的功能包括一个10Base-T连接、全双工通信接口,通过利用切换开关以便消除数据碰撞现象,并同步进行发送和接收数据信息;它还提供了64kb用户可配置存储器,采用RS-232和RS-485接口进行通信连接;具备本地操作员界面;以及可选择与Ethernet、DeviceNet和Profibus现场总线连接。
Mitsubishi电子自动化公司已经推出了新一代Q系列PLC系统,程序设计采用了基于Windows编程软件工具。程序通过USB接口进行传输。其特点是能够支持Internet电子邮件、调制解调器和10/100Mb/s Ethernet;可以连接到DeviceNet、Profibus、CC-Link和NET/10;每个CPU可以允许有不超过252个程序的同步运行;另外,它的体积也是非常小的。
CTC公司为工业用户提供了一套2601自动化成套工具,该工具包括增强型2601控制器和基于Windows平台的Quickstep SE程序开发工具软件包,Quickstep SE是该公司用于2601控制器具有专利的程序设计语言,尤其能够满足需要数字控制和串行通信的小型应用项目的应用要求。为2601所编写的控制程序只要通过相应的转换就可以运行于其他2000系列CTC控制器上。
一种新的来自于IDEC公司的产品是MicroSmart PLC,在该PLC的CPU模件上提供了10、16或者24通道的I/O。其特点包括一个标准的电源供应电路、4通道高速计数器、一个RS-232接口和一个模拟量分压计。具有24通道I/O的CPU模件也能够与总计不超过88通道的I/O模件一起工作。
来自ifm电子技术公司,并具有一对AS-I现场总线的主控制器包括两个采用IEC 61131-3标准编程以及依靠AS-I和RS-485通信的AC 1011 PLC。AC 1011采用了单个控制器方式,其I/O允许不超过124通道输入和124通道输出;而AC 1012则采用了双控制器方式,其I/O通道数量是AC 1011的两倍。
此外,许多PLC系统已经与操作员面板和其他HMI系统一起使用,在有些情况下,PLC的逻辑处理功能已经被直接集成到HMI软件中。
来自于B&R工业自动化公司的B&R PP21/41高级操作面板进一步结合了Compact PLC和HMI面板系统,并应用于集成低价格机械控制和操作员界面。它具备700kb的SRAM和1.2MB的FlashPROM存储器,采用了基于IEC 61131-3标准的程序设计语言、ANSI C和B&R自动化Basic语言进行编程设计工作。模件单元包括16通道数字量I/O,所具备的6个可利用扩展插槽用于附加的数字量、模拟量通道扩展以及通信I/O模件。串行和CANbus接口也同样被包含在其中。
EXOR公司也已经通过将一个PLC和I/O模件嵌入到一个叫做HMIcontrol集成系统的方式来扩展其UniOP系列HMI操作面板,PLC模件完全与其所有UniOP产品兼容,并使用了相同的、基于Windows平台、用于所UniOP操作面板的组态软件包。
十三、结束语面对激烈市场竞争所带来的局面,企业只有紧紧把握市场运行的脉搏,充分结合自身的特点,面向世界经济的大潮,不断融入新技术、新方法,推陈出新。同时,随阗PLC供应商的不断努力,并进一步在e-制造和e-控制技术方面实现新的突破,所推出的新一代PLC将能够更加满足各种工业自动化控制应用的需要。

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