In the past, PLC control and computer control have always been the two main control modes in industrial control. In the past, the process of monitoring the state of construction machinery by PLC control system is complex and time-consuming, thermostatic element which makes the working efficiency of construction machinery low and difficult to meet the requirements of intelligent control of modern construction machinery. Soft PLC, a new type of functional controller, has been widely used because of its unique advantages, which can meet the requirements of intelligent control of modern construction machinery. The development of software system, based on IEC61131-3 standard, supports five programming languages of PLC. The system develops and applies CIL technology. Through CIL converter, the programming language of PLC is changed into CIL language. Finally, it is converted into executable code by CIL. Operating system is the key of the whole system. Soft PLC technology realizes that the PLC system has the control ability of the previous PLC through operating system. On the one hand, it executes instructions and analysis, on the other hand, it realizes the management of memory resources and data resources. The software architecture of the controller is divided into three layers: the bottom CAN bus interface driver and the input-output interface driver, whose purpose is to realize the query status and the collection and transmission of data information; the real-time multi-task operating system, which mainly manages the running status of the CPU, realizes the time management, operation management and memory management; the PLC kernel implements the PLC program. 。 According to different functions, it can be divided into AI/DI interface, DI interface, PI/DI interface, PWM/DO/DI interface and DO/DI interface.
According to their respective functions, drivers are designed and corresponding interface parameters are set. DI interface realizes the input switching quantity of the external interface; PI/DI interface realizes the frequency of the input pulse quantity of the external sensor; AI/DI interface function monitors and controls the internal temperature and the external input power supply voltage, and reasonably controls its scope; DO/DI interface realizes the output of the low-level switching quantity; PWM/DO/DI interface, PWM means the output of pulse width modulation. The duty cycle of PWM signal changes the opening and closing degree of solenoid valve proportion. The state of all input points is stored in the corresponding address, and the CANOPEN data information is stored in the relevant address. Then the program is executed. The CANOPEN address value is transmitted to the CAN bus according to the address value of all output ports. JoyFilter module. Handle analog input processing function. The input of the handle is an analog handle. If the voltage is 6V, the median voltage is 3V, and the voltage changes from the median to the maximum voltage, from 3 to 6V, and from the median to the minimum voltage, it is 3 to 0V. In fact, the ideal reference voltage is not necessarily 6 V, and the change from median to maximum voltage is not necessarily 3 V. This module is mainly used in conjunction with the PWM function provided by the controller. The median maximum input value of the handle is set to 0-33 756, and the median to minimum value is set to 0-33 756. Motion module. The main purpose of this module is to control the proportional valve and output two channels of PWM. The range of signal is controlled between – 33 756 and 33 756. If the signal is controlled between 0 and 33 756, the output of PWM Up is 0 to 33 756.
If the signal is controlled between 0 and 33 756, the output of PWM down is 0 to – 33 756. The minimum and maximum output current range is determined by parameter control. Hardware has six kinds of signals at this stage: DO, PI, DI, PWM, Current Input, Voltage Input. Before that, add the equipment needed for testing, open the equipment library, install the equipment you need. After the installation is completed, you can click on PLC to see the equipment you installed, build a new project, and then determine the location of the project to be saved. Under the channel type setting, there are three choices: Digital Input, Current Input and Voltage Input.
The pin number channel function is set to Digital Input, the DI is tested, the type of Digital Input channel is selected, the remaining channels are similar, and the corresponding switches are found, and the function is configured as Digital Input. After configuring DI channel, install the PLC program, the terminal prints the configuration status of each different channel, inquires and checks whether the channel configuration is correct, and if the channel configuration is not correct, re-operate until the correct configuration is stopped. In this study, the hardware model of the intelligent controller for construction machinery is LPC2939 chip. The working frequency is relatively stable. The frequency is 130 MHz, the internal memory byte is 867 K, the random memory byte is extended 3 M as the system operation storage, and the FLASH memory is extended 1 M as the program storage. After developing the controller development board, it is more reliable after testing. After the hardware design of the intelligent controller for construction machinery is completed, it can meet the requirements of most construction machinery, and make full use of the internal resources of the controller. Most of the interfaces of the controller are reused with three functions, so that the application controller can be more suitable for different customers and different types of construction machinery. Convenient. A/D, I/O and PWM input and output interfaces, connected with CAN bus communication interface, can meet the current construction machinery switching, analog, digital acquisition requirements. CAN bus information acquisition and transmission structure can meet the requirements of CAN bus information acquisition and 2-way engine information acquisition. All the structures are closed structures, which have the advantages of anti-vibration, water-proof and dust-proof, and can meet the protection requirements of construction machinery.
The system design adopts modular mode and has strong reconfiguration ability, which can meet the control requirements of different mechanical engineering; the application of real-time multi-task embedded operating system can meet the requirements of real-time controller system; it is consistent with the development environment of IEC61131-3 standard PLC; the construction machinery controller realizes networked control and stabilizes CAN. The OPEN communication protocol and the intellectualization of field control satisfy the realization of timely protection, operation judgment and other functions in the field of emergency. DI test. By executing the PLC program, the initial value is TRUE, which indicates that the DI value is 1.
Clicking on the corresponding pin of DI, the value becomes FALSE, indicating that the DI value is 0, indicating that the DI test is successful, and the remaining pins can be tested in this way. DO test. DO signal in DI/DO signal on development board and DO signal in PWM/DO/DI. DO signal test in DI/DO signal, the pin resistance size test results can be output to 0 or 1. The DO signal test in PWM/DO/DI indicates that the pin voltage is high if the DO value is 1, and that the pin voltage is zero if the output value is 0. PWM signal test. When the frequency is 40 Hz, the duty cycle of PWM output is set and the definition parameter is PWM0=500. When the duty cycle of PWM is 30%, the waveform output is concave; when the duty cycle of PWM is 70%, the waveform output is convex. JoyFilter module test. Because of the function of scale, AI input of JoyFilter module is -33756-33756, which is a bidirectional input value. Based on this, the generated curve of JoyFilter module actually becomes JoyFilterac. The curve smoothness is not enough, because AI simulates the influence of input, but does not interfere with the normal output of the module. Motion module testing. When the parameters are 0.2, 0.05 and 0.02, the corresponding target current of the control signal changes from 0 to 800 mA. After analysis, it is concluded that the actual output current of the controller can reach 800 mA target current after a period of time, and it is stable enough. When the three parameters are different, the time for system stability is different. When the parameter value is 0.02, the system takes the longest time to adjust, which takes about 5 seconds; when the parameter value is 0.2, the system spends. The practice of fee adjustment is the shortest, about 1 s. When the parameter is 0.05, the practice of adjustment is between 0.2 and 0.02, which needs about 1.5-2 s. In this case, no overshoot occurs. Soft PLC technology, according to the platform division, there are three main schemes, namely hardware PLC system platform, EPC system platform / IPC system platform, embedded system platform. As shown in Figure 1, the main application of hardware PLC system platform, as a carrier, will be the soft PLC system, loaded into the hardware PLC system, software PLC system to achieve program download and program development. As shown in Figure 2, mainly through EPC and IPC systems, as carriers, soft PLC systems are operating in EPC and IPC systems, in order to achieve program download and program editing. The core modules of EPC and IPC controller software system are generally Windows, Linux and other operating systems. Embedded system is mainly used as the carrier, and soft PLC system is integrated into the embedded system. Soft PLC system is used to download and develop programs. Embedded operating system, such as Embeded Linux, is generally used as the core of the controller software system. In summary, the soft PLC control technology has solved the shortcomings of the traditional PLC technology, its open architecture, better network communication ability and stronger information processing ability. After the application in the field of industrial control, the production efficiency and automation ability of enterprises have been further improved.