1 Introduction

In the field of measurement of industrial production, online weighing control system is a very important measurement equipment in production, most of the traditional batching machines use fixed point-to-point wired communication, this type of equipment generally use RS485 bus for data transmission, a variety of instrumentation is connected through the wired way, so that not only on-site construction is troublesome, but also very high cost. With the development of computer technology and wireless communication technology, the computer control system based on wireless network transmission is used more and more. Currently on the market weighing control method is mainly used for hygroscopicity, particle shape uneven hook, specific gravity is not stable and high price of lump or powder solid measurement, in the domestic has developed a certain stage, to achieve a certain degree of automation level, but there is still a degree of automation is not high, the weighing accuracy is not high and so on shortcomings. In order to realize the automatic monitoring of the remote field equipment, the automatic weighing control technology and wireless communication technology integration, gives a design scheme based on the embedded platform and wireless communication module. The program adopts the embedded module ETW2232D, ETHO02 as the main devices to form a wireless monitoring system, which consists of four parts: weighing module, PLC, digital transmission radio module, and upper computer monitoring management. The system is composed of four parts: weighing module, PLC, digital transmission radio module and upper computer monitoring and management. The monitoring and control of remote weighing and batching equipment by means of digital transmission radio provides a new way for wireless remote automatic weighing and management. In this paper, a wireless interface weighing remote monitoring system is designed to combine embedded technology, wireless measurement and control technology and automation technology organically. The system has high weighing accuracy, strong real-time, high reliability, low cost, and has a wide range of application prospects.

2 wireless weighing mixer overall structure

Wireless weighing mixer is mainly composed of four parts, namely, feeding system, weighing instrument, wireless digital transmission radio module and monitoring computer. Feeding system mainly consists of two parts: storage bin, filtering mechanism and rotary conveying mechanism. The weighing instrument consists of preamplifier circuit, display circuit and microcontroller communication circuit. The function of the wireless digital transmission radio module is mainly to forward the data, receive and send signals between the weighing instrument and the computer in the central monitoring room. The weighing and mixing machine integrates computer technology, automatic control, communication technology and weighing technology into one, with perfect control function, centralized display and operation, convenient data processing, simple installation and maintenance, and easy expansion of the system, which solves the problem of centralized computerized dosage system, and achieves "centralized management and decentralized danger". The system is stable and reliable to meet the use in the continuous production process. Monitoring computer and wireless module communication between the RS232 converted to RS485 interface.

Wireless digital transmission module interface circuit weighing batching machine using YL-42L radio transceiver module, the module built-in TI's latest high-performance ETHO02 wireless communication chip, operating frequency: 420 ~ 430MHZ, the channel is license-free, low-power, barrier-free transmission distance of up to 1,000 meters or more can be applied to a variety of occasions.

Weighing module and wireless module communication between the direct use of TTL levels, through the serial port for data reading and writing, for the wireless digital transmission module to set the interface.

4 PLC programming and host group configuration design

The monitoring computer carries out a data collection of the weighing module through the serial port every 100ms, the monitoring computer transmits the collection instruction to the microcontroller of the wireless digital transmission radio module through the serial port, and then the microcontroller of the wireless module sends the received instruction to the ETHO02 through the SPI interface, and the ETHO02, in the transmitting mode, writes the transmitted payload into the TXFIFO, and adds the controllable data before the data packet ETHO02 will add the leading code, synchronized vocabulary and CRC parity check code of the controllable data in the packet, and then send out the packet. When the wireless module of the weighing controller receives the valid data, it will parse and send out the packet by leading detection, synchronized vocabulary detection and detecting CRC parity check code, and then the MCU of the wireless module will read out the received data from ETHO02 through SPI interface, and then send it to PLC through the serial interface. PLC, then PLC according to the received data to perform the acquisition of data and control peripheral equipment work. After the acquisition task is completed, the PLC sends the acquired data parameters back to the monitoring computer through the wireless digital radio module, and the monitoring computer carries out the functions of data display, data processing and report printing according to the received data information.

This system adopts two-stage dosing method, i.e. fast dosing and slow dosing, to shorten the dosing time and improve the weighing efficiency by fast dosing, and to reduce the weighing error and improve the weighing accuracy by slow dosing. The current weight in the system is set as M1, the target dosage amount is M2, the advance amount of slow dosage stop is M3, and the target amount of slow dosage is M2-M3.

It can transmit about 500 meters in the workshop environment of motor interference. The central computer monitoring software adopts Siemens WINCC configuration software to realize real-time collection of quantity data and centralized management of data 2-131. This system adopts 4 sets of weighing modules for the weighing control of bulk materials in mines, and the upper computer system realizes the following functions:.

1) Real-time display of data: including current weight, set weight and accumulated weight;

2) Communication status display;

3) Operation commands: system start, system stop, emergency stop;

4) Historical data: historical data view, historical trend and historical data table display;

5)Data report: daily report, monthly report, annual report;

6)User management: user authentication, user password modification, new user addition;

7)Parameter setting.

5 Conclusion

This paper adopts Schneider PLC as the processor of the batching machine with YL-42L radio transceiver module to realize the wireless transceiver communication function, and the upper computer adopts Siemens WINCC configuration software to realize the on-line automatic weighing and management of the belt conveyor line in the mine. The system provides a new way for automatic weighing and management of bulk materials (iron ore, copper ore) in mines by means of wireless digital radio for data acquisition and control of remote weighing equipment.