Analysis of PLC and data communication between the Intelligent Slave-PLC, Smart - Electrical industr
CPU315-2DP Siemens S7 series production of its CPU, integrated PROFIBUS-DP communication interface. AriCon211-DP is a Beijing gold from Tengen Intelligent Control Co., Ltd. (hereinafter referred to Kim from Tengen company) products, and its CPU is also integrated PROFIBUS-DP communication interface. The connection structure shown in Figure 1.
Recent years, with the rise of factory automation system, programmable logic controller ( PLC ) And Fieldbus In industrial control has been widely used. In the factory automation systems, general use PLC High reliability and simple modular structure and programming characteristics, as the lower computer time to complete acquisition and control tasks; the use of field bus system openness, interoperability and system architecture to build highly decentralized nature of open automation interconnection system. Control system is the master and slave structures frequently used means of communication, but in the past from the station by the main station only a simple stored procedure to run, if the failure of the main station, from the station can not continue to work, so the entire system the ability to work down a row, is not conducive to the growth of enterprise efficiency. To solve this problem, can change with a CPU with an intelligent DP slave, not only to achieve independent PID control, can also receive the PLC Profibus master or PC master control data, form a digital, intelligent way, multi-point Communicate System, fieldbus networks, to achieve optimal control, and DP slave with high reliability, strong power of resistance, cost-effective, easy maintenance features, which can solve the above problems.
1 communication structure CPU315-2DP Siemens S7 series production of its CPU, integrated PROFIBUS-DP communication interface. AriCon211-DP is a Beijing gold from Tengen Intelligent Control Co., Ltd. (hereinafter referred to Kim from Tengen company) products, and its CPU is also integrated PROFIBUS-DP communication interface. The connection structure shown in Figure 1.
Figure 1 Connection diagram of the system communication structure
MPI: MPI (MultiPointInterface) cable to connect PC, and CPU315-2DP serial communications port. It is produced by a Siemens PC adapter to the serial port into a PC-MPI protocol.
RS232C: RS232C (RS said RecommendedStandard, C defined by a representative of the latest model RS232) PC, and communication is the most widely used in industry as a serial interface. It is defined as the connected data terminal equipment (DTE) and data circuit equipment (DCE) cable in the electrical characteristics of the signal is a low-speed serial communications to increase communication distance of the single-ended standards, to take unbalanced transmission, the single-ended communication. RS232C for transmission at close range. Connection shown in Figure 2.
Figure 2RS232 serial interface connection PROFIBUS-DP (ProcessFieldBus): using RS485 transmission technology communications, baud rate selectable 9.6Kbps ~ 12Mbps, the maximum cable length depends on the selected baud rate. Both ends with terminal transmission line resistance, medium with shielded twisted-pair cable. At this level, PLC high-speed serial line with the decentralized field devices to communicate.
2 hardware 2.1CPU315-2DP Its main memory of the maximum storage capacity of 512KB, CPU can process up to 82K statements, and to provide maximum 8192 marks, 512 timers and 512 counters. CPU can also extend to 1024DI/DO or 128AI/AO. It can also be used the most powerful features of a PROFIBUS-DP integrated interfaces to, and serve as the primary device or from the device settings. Up to 125 PROFIBUS-DP station connected to the main equipment. Data transfer rate of 12Mbps. Distributed I / O to the central I / O exactly the same way (ie, STEP7) configuration and programming. It is the communication protocol chip SPC3 DP Agreement integrates FDL layer, you can take part of the microprocessor communication load, to achieve DP slave communications processing.
2.2AriCon211-DP Can meet the IEC61131-3 programming standard AriOCS its configuration with high flexibility, you can connect 32 modules (digital I / O, analog I / O, pulse counting, communications, etc.). With fast scanning cycle, can be connected to additional external memory, without MPI adapter. Maximum transfer rate of 12Mbps. Good data to use the RS232C configuration to the modules CPU of downloading.
3 software components Posed by the PROFIBUS fieldbus bus controller software includes: PROFIBUS bus device configuration software, driver software, configuration software and application procedures. They have the following features: the main station and remote from the station parameter settings, master data from the station to read and write, graphics configuration, database creation and maintenance, statistics, report printing, fault alarm, application development, debugging , running, etc.. Among them, the configuration software and driver software provided by the equipment vendors, configuration software can be used such as general-purpose software STEP7.
This experiment all of the software are based on MicrosoftWindowsNT system, with good user interface, its function is very comprehensive and practical, easy to use.
3.1 programming configuration software STEP7
STEP7 is a set of Siemens SIMATIC industrial software development. It is very powerful, not only to switch traffic for a perfect command, and when dealing with analog rich instruction. You can use any programming language, such as STL (statement list), FBD (function block diagram) and LAD (ladder diagram), can be arbitrary switching from one language to another. Hardware configuration tools and test equipment and working methods of the switching instruction set (there is a wealth of instruction), even very complex functions can be easily programmed. Addresses the distribution and installation of the modules configuration is a Siemens STEP7 Manager function, where the module as a practical system in the PROFIBUS master. MPI completed works through the serial port to send CPU.
3.2 configuration software AriOCS AriOCS is gold from Tengen developed exclusively for IEC1131-3AriConCPU21x programming configuration software, using IEC standard specifies the five languages. It supports online and offline simulation debugging modification, debugging is very rich, with online help function. In addition, it comes with a parameter configuration software WinNCS.
3.3GSD file
PROFIBUS devices have different performance characteristics, mainly in the existing functionality (ie I / O signals of the number of
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