The application of force control @ in motor monitoring system
Abstract: This paper introduces the application of three-dimensional force control pcauto3.1 configuration software in frequency converter network to motor monitoring, and introduces its implementation methods: communication protocol, realization of group state monitoring, application prospect, etc
Abstract: In this paper, it is introduced the application of supervisory control configuration software pCAUTO31 for the Inverters Nets for motor supervisory and control, And the application ways: the communication protocol，the application of supervisory and the foreground is introduced .
keyword: configuration; RS-485; Frequency converter
Key Words: configuration ; RS-485 serial communication ; the Inverters.
with the development of industrial automation, computer network and DSP technology, frequency converter, as an important means of AC speed regulation, has been more and more widely used in industrial production. Nowadays, the energy shortage in the world has become a global problem, and energy conservation is more important. The application of frequency converter can replace the traditional wind deflector and throttle valve for fans, pumps and compressors in electric power, petroleum, chemical industry, metallurgy, water resources and other industries. It can timely control the air volume and flow according to the load, and significantly improve the energy-saving effect. In addition, it can also improve and adapt to the operating environment, smooth acceleration and deceleration, and improve the displacement change technology of the processing record. The control function of the frequency converter network is to connect multiple frequency converters with the upper computer through the serial port. The upper computer operates, monitors and alarms multiple frequency converters in real time, and can embed Profibus and other field buses, which improves the flexibility of control
the three-dimensional force control pcauto31 configuration software is the earliest software used in the Internet in China. It is a configuration software based on b/s application. It is also the largest PC based configuration software controlled by "soft PLC" with the most application cases and the largest scale in China Hmi/scada configuration software [1.
the inverter network introduced in this paper: each inverter can drive 1~2 motors; the network is controlled by RS-485, and the daisy chain mode can be used to connect up to 31 inverters, with a maximum communication distance of 1.2km. Figure 1 shows the control network composed of the upper computer and multiple inverters through RS-485. The upper computer uses the powerful real-time database function of pcauto31 to monitor the real-time running status of the motors.
2 the system requires that
the In the later stage, the motors at each position in the control network will also build a waste lithium material recycling project in Suining, including forward and reverse rotation, start-up, shutdown, acceleration and deceleration, fault alarm, historical trend, data sharing, etc., so as to realize automatic report generation and efficient production management. It makes the production process easy to operate and reduces the cost of control and maintenance
3 communication protocol
the upper computer acts as the host to monitor the operation of the frequency converter, and the frequency converter acts as the slave. RS-485 half duplex mode is adopted
the communication setting can be set to the same by the frequency converter and the upper computer. The transmission speed can be set from 1200BPS to 19200bps; The data length can be 7 or 8 bits; Parity check can be set as no check, odd check and even check; The stop bit can be 1 bit or 2 bits; No response time can be set to 1s to 60s; The interval time can be set from 0s to 1.00s; Communication errors include checksum error, parity error, format error, timeout error, command error, link priority error, function code error, data error, etc
each frequency converter is given a unique station address, and it can only be put into use after passing strict tests, waiting for the microcomputer to select (write) or query (read) status. After receiving the request frame from the upper computer with the same address as its own station, the frequency converter determines that the request frame is received normally, and then returns the positive response frame (if it is a query frame, the data and response are returned together); Otherwise, a negative response frame is returned
the communication protocol realizes the following functions: read out all the parameter settings of the frequency converter and the basic parameters of the controlled motor; It can start, stop, accelerate and decelerate, reset, etc; It can monitor the current operation status, including motor output frequency, set frequency, output current, output voltage, torque current, torque calculation value, operation command, etc. The communication protocol includes two types of frame formats: standard frame and optional frame. Each type includes selection frame and query frame. Each type of frame includes request frame and response frame. All the characters that make up the frame are represented in ASCII code. The standard frame is applicable to all communication functions, and the selected frame is only used for input of inverter command and monitoring during high-speed communication
where the start bit represents the start of the frame (01h); Station address bits of 2 bytes include ten bits and one bit (1~31) of station number; The request bit indicates the request from the upper computer to the frequency converter (05H). If yes, the bit is 06h, and if no, the bit is 15h; Command bits include read, write, high-speed write and alarm reset; Category bits include basic functions, control functions, advanced functions, setting data, monitoring data, etc; The number bits of 2 bytes represent ten and one bits of the data number to be obtained; 4-byte data bits represent the data to be written or read out; The check sum bit of 2 bytes (composed of check sum, ten bits and one bit) is used to check whether there is an error in the communication frame during data transmission. Calculation method: except for the start bit and check sum, the bytes of other fields are added one by one, and the lower bytes are taken, and then represented by ASCII code. For example, if the above sum calculation result is 1234h, the ten bits of the check sum are ASCII code "3" value, and the one bit is ASCII code "4" value. Figure 2 shows the flow chart of query execution on the host side
the station address bit in the frame is selected. The request bit and check sum bit are the same as those in the standard frame, but the command bit is different
this design uses RS-485 to connect multiple frequency converters into a network, so there is a special broadcast frame in the communication frame of this design for this function, just like setting the input operation command and frequency command of all frequency converters. The broadcast frame format is the same as the standard frame format, with the difference that the "station address" bit is set to unit 99