Soft PLC and the distinction between hard-PLC
Soft PLC control technology
Abstract: The open CNC system CNC Technology is the current hot spot. In the development of high-speed performance such as high precision and intelligent at the same time, function and development also requires more and more strong, as embodied in the NC software to all the features to minimize the hardware size. The PC as the hardware platform, with software to implement the function of PLC (ie, soft-PLC) in an open CNC system PLC trends. Describes the composition of soft PLC technology and application features, and its technical advantages and constraints of technological development were analyzed to explore the soft PLC applications in industrial control program. Soft PLC running the program compiler and simulation efficiency is higher, and display hardware PLC incomparable superiority, very suitable for open NC system
Key words: Soft PLC control technology control software program editing environment
1. Software PLC Technology Background
The 20th century, late 90s, people gradually realized that the traditional PLC (the paper referred to hard-PLC) such as the existence of its own drawbacks: difficult to build an open hardware architecture; staff must be a long-time professional training to master a particular programming products; traditional PLC production was monopolized by a few companies, resulting in cost-effective PLC's growth is slow. These issues have become the factors restricting the development of the traditional PLC. In recent years, with the rapid development of computer technology and of international standards PLC, a PLC to break the traditional limitations of the new technology developed, this is the soft-PLC technology. Its features are: PLC functionality while retaining the premise of the field bus network-oriented architecture, using open communication interfaces such as Ethernet, high-speed serial ports, etc.; using a variety of relevant international industry standards and a series of facts the standard; all software to achieve the traditional PLC functions.
2, system architecture and application characteristics
2.1 System Structure
Soft PLC based on PC, based on certain operating system platform, through software calculation methods of traditional PLC, control, storage and programming functions, through the I / O modules and fieldbus and other physical equipment to complete the on-site data collection and signal output. The composition according to the traditional PLC, Soft PLC system and operation of the system by the development system composed of two parts. Editing environment can be divided into two parts and the operating environment. Editing environment and the operating environment is a client / B server model, used between the COM / DCOM communication mechanism, operating environment as a COM server, and provides a standard communication interface; editing environment as a COM client application to access the local or remote access interface to download code, read the operating environment to run information operations. Embedded systems are usually from the EPC or the embedded controller (also called intelligent controller) and embedded software components, embedded software is divided into the embedded operating system and embedded applications, embedded operating system process is characterized by short, required less memory, Microsoft has introduced the WindowsCE is an embedded operating system, while the soft PLC can be used as an embedded application running on embedded systems.
Soft PLC development system and run the system are mutually independent and inseparable two applications can be run separately.
Soft PLC Development System 2.1.1
Soft PLC system is actually developed and compiled with debugging features PLC programmer, this section has the following features: ① standardization of programming languages, follow the IEC61131-3 standard, multi-language programming (a total of 5 programmatically: IL, ST, LD, FBD and SFC), programming languages ??are interchangeable; ② rich control module, support for multiple PID algorithm (such as the conventional PID control, adaptive PID control algorithm, fuzzy PID control algorithm, intelligent PID control algorithm, etc. ), but also a number of popular control algorithms such as neural network control; ③ open control algorithm interface, allowing users to embed their own control algorithm module; ④ simulation run, real-time online monitoring, online modification and compiler; ⑤ strong network function. Supports TCP / IP network, through the network PLC remote monitoring, remote program changes.
2.1.2 operating system software PLC
This section is the core of the soft PLC to complete the input processing, program execution, output processing and so on. Usually I / O interface, communication interface, system management, error management, debugger kernel and compiler components: ① I / O interface with any I / O system communications, including local I / O system and the remote I / O systems, remote I / O, mainly through the field bus InterBus, ProfiBus, CAN, etc. to achieve; ② communication interface. Through this interface allows the operating system or development system can HMI (or MMI) software in accordance with various communication protocols, such as downloading PLC program or data exchange; ③ System Manager, to handle different tasks and coordination of program execution, and from I / O read and write variable image; ④ error manager, detect and process various errors occurred during the execution; ⑤ debug the kernel, providing multiple debugging functions, such as rewriting, forced variables, set breakpoints, set variables and address of the state ; ⑥ compiler development system is usually written in the middle of PLC source code, compiled, and then run the system to compile the intermediate code translated into the hardware platform machine executable code (ie object code).
(Editor：admin) |