Embedded PLC?? Embedded Type PLC
Abstract: Based on the classic controller analysis, the concept of embedded PLC, key to EASYV1.00 embedded PLC software kernel structure for the basic analysis to guide the industrial designer to create a new embedded system design.
Keywords: Embedded PLC kernel CAN bus
Abstract: Bytheanalysisoftheclassicalcontroller, theconceptionofembeddedPLCisproposed.TheemphasesistoleadthedesignersofthecontrollingengineeringtobuildanewnotionofthedesignofembeddedsystembythebasicanalysisofthekernelconfigurationoftheEASYV1.00embeddedPLCsoftware. Keyword: EmbededPLCKernelCANbus [CLC] TP23 [Document code] A Article ID 1606-5123 (2005) 11-00
1 Introduction: the concept of embedded PLC
Embedded PLC refers to a control device to achieve a specific PLC (ProgramableLogicController) ladder programming language interpretation, implementation, so that a particular device has its own special features based on the basic functions of PLC.
Ladder is an engineer for the factory automation, graphical PLC Programming Language. Ladder with simple, intuitive, process-oriented, and many other advantages. PLC programming language to control the emergence of the hardware device management and control processes for the separation, PLC manufacturers to focus on hardware and hardware management, factory automation personnel using ladder language for secondary development, so the same applies to the different control PLC system, the formation of a programmable logic controller (PLC) of this platform-level products.
But the control of product design has developed into a pursuit of personalized, differentiated design stage. Conventional PLC can not enter the market, often face more of a personalized, differentiated pressure. Such as cost control, and special functions. Emergence of industrial computer (IPC), microcontroller, embedded boards closer to the individual needs of the control products. IPC in the interconnect, the expression of the algorithm so obvious advantages in cost control MCU system more flexible. IPC The loading of the operating system (such as NT) when in fact, stability is difficult to meet the demanding requirements of continuous control, usually used for monitoring. Lower usually PLC. SCM system, the hardware management and user control of mixing process, limiting its standardization, and ultimately loss of cost competitiveness.
Is embedded PLC and microcomputer systems development for the IPC, which retained the PLC (with ladder language) hardware management and process control advantages of separation, combined with IPC and single chip to provide a more personalized and differentiated designs method to form a new controller design. When we IPC embedded PLC functionality, we call on PCBase embedded PLC, when we embedded PLC functionality in SCM, we call on AllONOne embedded PLC (chip-level embedded PLC). When not specified, refers to film-level Embedded Embedded PLC PLC, which is proposed in this paper an embedded PLC. The following description of an 8-bit microcontroller C8051F040 to Kuwait for the hardware companies EASYV1.00 Edition Embedded PLC software architecture.
Currently, there are soft on the special PLC PLC PLC and two passenger standard. Soft PLC refers to high-end general-purpose real-time embedded operating system with PLC software, customer-standard PLC is designed according to user needs orientation PLC. Related technology in Germany, Taiwan, South Korea had breakthrough areas are embedded PLC.
2 Embedded PLC software architecture 2.1 overall structure EASYV1.00 embedded PLC is a powerful real-time operating system software, the structure consists of three levels, shown in Figure 1.
(1) Embedded PLC kernel real-time task scheduling is completed, ladder language interpretation, implementation, communication and other basic functions, and provide secondary development-driven interface;
(2) secondary development program provided through the core plug-task, using a variety of kernel development for individual differences in the specific object of the driver;
(3) termination for process control applications that the ladder language programming;
The overall structure of Figure 1EASYV1.00
Developers for the second object for the individual driver, must understand the Embedded PLC kernel structure, especially the drive interface design method, the following block describes the kernel of the block function.
2.2 Real-Time OS For small microcontroller, real-time operating systems generally can not be loaded, OS / take up too much resources, EASYV1.00 core according to the type of task, real-time requirements, customized a special real-time OS, it is no documentation system and memory management in two parts.
(1) hard real-time concurrency under the preemptive task management
EASYV1.00 kernel benchmarks provide 2.5ms time base, it can not be deprived of the task as a loop for the various tasks of monitoring and management.
For industrial applications with asynchronous events concurrent task management, through various interrupt preemption task hangs, execution, execution of each type of asynchronous task before the task in the 2.5ms of registration, after the cancellation, by 2.5ms Time-based traffic monitoring and blocking concurrent tasks and report status of the word to the next level task scheduling.
(2) EASYV1.00 the asynchronous task
Communication data link layer of the byte stream contact
Ladder language Timer ? Secondary development in the driver's real-time asynchronous tasks
Concurrent task management is EASYV1.00 the lowest level of task management, to ms-level real-time effects, per unit time (1ms) CPU-machine peak:
T and = Ni?? 1ms maximum number of times within the task, ti?? An implementation of the maximum time the task.
EASYV1.00 concurrent tasks real-time data in Table 1, Table 2.
Table 1EASYV1.00 concurrent tasks real-time data
Task category inalienable task of the task communication byte stream concurrent tasks ladder timer driver
2.5ms time base serial port 0 serial 1CAN
Number of times (N1) 11111ND Execution time (T) 10 s + T25 s25 s50 s40 stD
Table 2EASYV1.00 concurrent tasks real-time data
Task type ladder communication function call the user software interrupt Number of 131m4
tasks Task time 1-20 s1-10 s1-5 st4
T film = 3-45 s + t4
T
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