The automatic weighing and metering of electrolyte is realized by using the micro PLC-FX3UC and microcomputer produced by Mitsubishi Corporation, combined with pneumatic, weighing module and position control technology. The paper mainly introduces the hardware and software design of the dosage system and provides the main hardware principle. The dosage function is advanced and practical, and has good application prospects.

1 Introduction

An electrolyte production company, the liquid weighing and measuring is realized manually, which is not only inefficient and consumes manpower, but also due to the fact that the liquid production speed of each dosing production line is more than 60 tablets per minute, and the manual weighing can only weigh a small portion of the liquid, so there are always some defective products flowing into the next production process, which reduces the qualification rate of the finished products and increases the production cost. The automatic weighing and metering of liquid based on PLC control introduced in this paper improves the degree of automation and efficiency of the liquid production line, reduces the rate of defective finished products, and thus enhances the market competitiveness of the enterprise's products. This dosage system is applicable to dozens of specifications of electrolyte liquid automatic weighing and metering, that is, the liquid can be automatically weighed and metered parameter data are: length range of 60 ~ 175mm, width range of 20 ~ 70mm, thickness range of 0.2 ~ 0.5mm, the quality of the range of 8.00 ~ 60.00g, the precision of weighing can be up to 0.01g, the liquid can be weighed per minute 60 ~ 80 Pieces.

2 dosage composition and control process

2.1 Composition of dosage

According to the equipment and process requirements, the weighing and dosing system includes electrical and mechanical parts, of which the electrical part includes computer, PLC, weighing module, solenoid valve and motor, etc. The computer is used to monitor the whole system and PLC is the control core of the system; the mechanical part includes initial transportation belt, 1#～4# feeding transportation belt, qualified and unqualified and unweighed liquid receiving transportation belt, receiving box, Various cylinders and guide rails and brackets.

2 control hardware design

2.1 Upper computer

The upper computer adopts microcomputer for monitoring the whole control dosage system. It mainly realizes the functions are:

1) Display function: electrolyte type and liquid specifications and quality, equipment operation status, operation mode, alarm display and other functions;

2) Alarm processing function: record the alarm occurrence time, alarm content

(including the equipment itself fault and unqualified liquid too much fault, etc.);

3) report generation function: the report records the quantity and quality information of each specification liquid, and randomly select a batch of data to automatically draw X ~ R quality control charts, including the Times, Daily News and Monthly News, etc., are stored in the microcomputer hard disk for inspection;

4)Operation control function: Modify the parameters such as electrolyte model and liquid specification, etc. According to the buttons on the interface, the equipment can be operated, including automatic/manual switching of dosage system, starting/stopping, and the operation of on-site equipment action under manual state;

5) Management authority: realize different levels of management authority of dosage system, the operator of dosage system can choose liquid specification, operate the equipment, check the report and X~R quality control chart, etc.; the engineer of dosage system can modify the monitoring software and the software of the lower computer.

2.2 Lower computer

The lower unit is the core of batching control, which is composed of PLC and its extension module.

1) The main control core of the batching system adopts the latest micro-programmable controller FX3UC-32MT-LT produced by Mitsubishi Corporation, among the micro-programmable controllers produced by Mitsubishi Corporation, this PLC has the most powerful function and the fastest instruction running speed, and it can realize the complex data processing and arithmetic, and it comes with RS422 interface which can be used to write, debug and monitor the PLC program directly, and it comes with RS232 interface, which can be used to write, debug and monitor the PLC program. The RS422 interface can be used to write, debug and monitor the PLC program directly, and the RS232 interface can communicate with the upper computer directly, without the need for additional expansion of the communication module. It comes with 16 input points and 16 output points with fast response time, i.e., the response time of each point is less than 2 milliseconds.

Input and output points can be expanded to a maximum of 256 points. The basic instruction execution speed of this PLC is only 0.065 microseconds/article, and the longest execution time of each application instruction is only a dozen microseconds, which can satisfy the strict requirements of time for the control of this dosage system.

2) Extended input/output module: three 16-point digital input units FX2N-16EX, two 16-point digital output units FX2N-16EYR, and one 4-point analog input unit FX3UC-4AD are used for digital input/output for switching detection and control of the batching system, and the analog input unit is used for detecting the weighing signals.

1) Power supply unit: FX3UC-1PS-5V power supply module is selected to supply power to the main control core FX3UC-32MT-LT and analog input unit FX3UC-4AD, and 24V switching power supply is adopted to supply power to FX3UC-1PS-5V power supply module and digital input/output expansion module.

2) Variable allocation table: The PLC variable allocation of this control dosage system is shown in Table 1.

3 dosage software design

3.1 Upper computer monitoring software

The dynamic data display window is set up to collect data from PLC in real time, issue control commands to PLC and monitor the operation of the batching system, etc. The functional block diagram is shown in Fig. 3. The functional block diagram is shown in Figure 3.

3.2 Programming of lower PLC software

According to the production process and control requirements, to realize the automatic control of the whole feeding system, the feeding system adopts PLC ladder diagram programming to realize various logic sequence control and weighing detection control. The main program flow chart of dosing software control is shown in Figure 4. The control system can realize automatic/manual switching and various operations in manual state, so as to meet the production requirements.

4 Conclusion

The dosage system has the following innovations: simultaneous weighing and measurement of liquid groups controlled by PLC; high reliability and anti-interference ability of signal transmission between PLC and host computer; the start/stop of dosage and the control of auto/manual are controlled by direct operation of host computer, which reduces the hardware cost of this dosage system.

The electrolyte liquid automatic weighing has been installed and debugged on site, and is now running well, meeting the expected process requirements and economic benefits. The dosage operation is simple, open and cost-effective. The PLC control system gives full play to the advantages of reliable operation, flexible detection and easy maintenance. The successful application of the dosing system shows that PLC in the traditional industry technology to change the selection of a great deal.