Due to the frequency converter Inverter Win9X Mitsubishi has Inverter Win9X Mitsubishi excellent control characteristics and its high efficiency and energy saving characteristics of the inverter in recent years in various fields has been widely used. In some occasions, need to use a computer and clever work to control a plurality of frequency converter, in order to achieve the purpose of AC motor control. In the oil control system, inverter control problem becomes the key, in accordance with the previous control methods, need to control the inverter with PLC or control circuit board. However, using this method high cost, complex system, large wire, high failure rate, so urgently needs a kind of simple structure, low cost, high reliability of the system to achieve control of the inverter.
In response to this need, some companies (such as Japan's Mitsubishi, Siemens of Germany, Japan's Toshiba, etc.) launched the frequency converter with RS-485 communication interface, users can conveniently flexible choice of frequency converter of powerful, design their own industrial control system. Therefore, we can make full use of the manufacturers to provide industrial bus interface, the control system wiring simple, stable and reliable.
At present, we in the use of industrial bus user program interface, most of them are based on the DOS environment, with the popularity of the windows operating system the DOS single task system inherent defects has become increasingly prominent, people more and more hope to industry control in Windows environment.
Development of industrial control software in Windows 9x can not only realize multi task operation, make full use of the hardware resources, and can use the Windows 9x rich development tools, easy to generate various kinds of menus and friendly graphical interface, software product quality high and short development cycle. But under Windows 9x environment, the system completely over the hardware resources, does not allow the user to directly control the hardware system. How to develop the microcomputer of underlying resources under the environment of windows 9X/NT, has become a current controlling industry worth exploring the subject.
The serial communication between Mitsubishi Mitsubishi FR-A500 inverter as an example, using Visual Basic 6.0 ActiveX controls - Microsoft communication control by analysis of frequency converter with serial communication protocol, to solve the serial communication with a plurality of inverter under the environment of Windows 9x, successfully realizes the single PC for AC asynchronous motor flexible control, made beneficial attempt to under Windows 9x environment how to realize serial communication.
2, the introduction of oil control system of oil field
Because of the control technology of the multi inverter is the key to the oil transportation control system, it is necessary to simply introduce the general situation of the control system.
1 the central controller, mainly an industrial control computer and its communication module, it is mainly responsible for sending control instructions and control parameters, and according to the field return data to adjust the control parameters;
2 the monitoring signal and the pipeline feedback signal are connected to the central controller by the RS 485 bus;
3 pump station 1~n main oil pump, frequency converter, communication adapter, pipe sensor, etc.;
Control system communication principles
According to the requirements of oil control system, we give the communication block diagram (Figure 2), here only focused industrial PC and inverter RS - 485 interface of RS - 485 drive with 32 receiver. The baud rate is a bit, the communication distance can be up to 1200m. Communication distance is 15m, baud rate is up to 10mbit / S. in the industrial field, RS-485 is widely used as a way of communication.
In PC through RS-232C, RS-485 converter and a frequency converter is connected and up to 32. Each inverter is endowed with respective address code for identification, so that PC can through the RS-485 communication lines, to hang in all of the above frequency converter control operation.
Analysis of serial communication protocol converter
The oil control system structure design, and Research on Mitsubishi Mitsubishi FR-A500 inverter principle and communication modes, we found that Mitsubishi Mitsubishi FR-A500 inverter communication mode for asynchronous half duplex RS - 485 protocol; baud rate 19200bit/s, 9600bit/s, optional 4800bit/s; ASCII 7 or 8 bit data bit selectable; 1 bit parity optional; 1 or 2 stop bits are optional. The communication protocol of data format, there are ten kinds of, respectively is: A, a ', B, C, D, e, e', F, G, h;
Control system design of communication control software
Serial communication programming
Of industrial computer serial port programming must be based on the analysis of system structure and converter serial communication protocol. Under the DOS operating system, all computer hardware for the programmer is transparent, so relatively easy were memory management and hardware interrupt management, so the response speed is fast. However, DOS is single tasking operating system, serious waste of hardware resources, and graphical interface programming in the difficulty of the task and are far more than the programming of hardware. So we use Windows 9x operating system and on this platform and GIS software to write the software of the control system.
Under the environment of Windows 9x, operating system completely taken over the various hardware resources, does not allow the user to program directly read and write hardware port and interrupt management. So the early programmers only by a large number of API functions to control the port, use is very convenient.
The system use VB6.0 provides an ActiveX control (Microsoft communication control, referred to as MSComm control to realize the serial communication design. By means of embedding the MSComm control in the application program, through the serial interface of the computer and communication management. Below is a brief introduction about the MSComm control function:
6.0 MSComm control to realize the data buffer management, input from the buffer read received data) data type is variant, from the buffer read data format string format (text or binary format (binary).
Serial number (CommPort) is set to 1,2... N and so on, said COM1, COM2... Number of readout is.InputLen data read from the (effective number of bits (COMn. parameter settings for the (settings) format as "BBBB, P, D, s, BBBB baud rate, P indicates parity n: no parity, e: I check, O: odd parity), D expressed in bytes, s represents the number of stop bits. The serial port status PortOpen bool variable to true open serial port, false indicates close the serial port.InputMode program conveniently buffer format and set to 0, for string format (text), is set to 1 for binary format (binary) sets or returns the input from the buffer reads the string each character and the nature of the readout data block fixed length data string is very useful.
InBufferCount and OutBufferCount for serial port of the query mode. For more complex communication tasks, by Com9Xvent processing the serial events, when the relevant event or serial error event occurs, the system will activate the OnComm event, OnComm in add user code, you can achieve similar to the DOS interrupt serial processing program.
Converter serial communication software
In order to control a serial communication operations by the control, it is also necessary to insert the control in the application. Therefore, the MSComm control is inserted into a program of a dialog box, and for the control object naming MSComm1, then program in operation on the serial port, all can be based on as MSComm1 to achieve.
In this paper, using the Win9X serial communication function under the control of the ActiveX and MITSUBISHI inverter RS-485, successfully realized in Win9X environment under IPC control for multiple MITSUBISHI inverter, and can detect the real-time running state of inverter. The control system is flexible and convenient, it is very practical. This paper under Win9X design scheme inverter control and software realization of the good exploration and attempt to solve such problems. Compared with DOS, with short development cycle, make full use of hardware resources, the advantages of the software interface is beautiful. But because Win9X is a multi task time-sharing operating system, so the system can achieve real-time control of the strong. Is the future improvement.