To realize PLC, encoder and inverter synchronous control method - Database & Sql Blog Articles

Programmable Package SG-8018CA(SG7050C) 0.67M~170M

RF cable can be customized for other specifications

Photocoupler

Plc, encoder, frequency converter realizes synchronous control method introduction: Inverter and programmable controller control the motor speed through RS485 communication connection; programmable controller changes the inverter frequency according to the field speed measured by the encoder; The touch screen sets the working parameters.

1. Introduction to the working principle of the device.

The purpose of the equipment is to print subsequent processing, automatic laminating machine.

The working method is to coat the surface of the sheet of paper with a plastic film to make the surface of the printed matter look brighter and protect the graphic surface of the printed surface. For example, the packaging label of salad oil, or the cover of some books.

First, the sheets of printed sheets are conveyed straight to the peritoneal roller, and then the pressure applied by the rollers is used to bond the paper to the film. Finally, the paper is cut at the seam of the film, and the specific process is not described.

2, the main technical difficulties. Since the sheets are conveyed one by one to the drum, the film is wound around the surface of the drum so that they fit together and there is no gap between each sheet. In layman's terms, a piece of paper is attached end to end on a roll of film. The paper is conveyed straight to the drum, and the film is attached to the drum by an unwinding mechanism and then pressed against the surface of the paper.

Here, the linear paper feeding mechanism and the drum are respectively driven by two variable frequency motors, so the surface speeds of the two moving mechanisms are required to be uniform. Only in this way can there be no gap between the papers after the peritoneum, and the control accuracy requirement cannot be greater than 1 mm. The length of the paper can be set. For example, one time is to request 10,000 sheets of the same length, and the next time it is possible to use another length of paper. The diameter of the drum is determined to be constant.

The equipment is equipped with two rotary encoders to detect the linear speed of the paper feeding mechanism and the drum respectively. The plc adjusts the output frequency of the inverter according to the calculated speed to keep their linear speeds consistent. In the calculation process, due to the existence of the pi, the calculated data must be rounded. In this way, after multiplication and division calculation, more accurate data can be obtained. Data rounding in the calculation process can only obtain a more accurate quotient by expanding the data by 1000 times or 10000 times at the same time.

The dividend of plc is limited and cannot be too large, otherwise it overflows. Select a 1000p/r rotary encoder here. It is possible to directly divide the length of the paper into 1000 parts. And expand the data by 1000 times. These are selected during the specific design process. Just explain here. No longer calculate the data one by one.

According to the data calculation results, the two data are compared continuously. According to the comparison result, the frequency of the inverter is increased or decreased, so that the surface speeds of the two mechanisms are consistent. The comparison period is 20 milliseconds, and the frequency unit of addition and subtraction is 0.01 Hz.

3, the system consists of. Two encoders, respectively input two high-speed counting channels of plc. The two inverters change the frequency through the rs485 communication port of plc to form a simple closed-loop control system. The specific connection between the plc and the inverter through 485 communication is not specified here. You can refer to the modbus communication protocol and the inverter manual that supports it. The specific method will be communicated to you in future articles.