Design scheme based on NA200 series PLC in foreign fiber removal machine

With the programmable controller (PLC: ProgrammablelogicController) from scratch, the function from weak to strong, the application field from small to large, it has become the mainstream control equipment in the field of industrial control, playing more and more in all walks of life Great role.

1.1 The necessity of PLC application

As a kind of equipment for removing foreign fibers in cotton, the cotton foreign fiber removal machine mainly replaces all kinds of foreign fibers contained in cotton, thereby ensuring the quality of the yarn. As a production quality control equipment, cotton foreign fiber removal machine is the primary requirement for its operational stability and equipment operability. First, once the equipment is not operating properly, it will not only affect the output, but also cause the yarn quality to drop. Therefore, the control unit of the equipment must use reliable devices. Second, the operation method of the equipment itself and the cascade control method with other equipment on the production line need to adapt to the operating habits of the textile factory workers, and try to start and stop as much as possible. Based on the above requirements, the cotton foreign fiber removal machine adopts PLC as the logic control unit to meet the design requirements of the equipment.

1.2 Features of NA200 Series PLC

As a small integrated PLC product, the NA200PLC includes a single CPU module and a variety of optional expansion modules that can be used to implement powerful and complex control functions whether they are operated independently or connected to each other. This series of PLC has the following characteristics: 1 high reliability, strong anti-interference ability, suitable for use in various industrial sites. 2 complete set, complete functions, strong applicability. The CPU body has a variety of I/O specifications to choose from, as well as high-speed counting, timing, standard RS232 and RS485 interfaces. A variety of expansion modules are available. 3 Support ladder (LD), instruction list (IL), function block diagram (FBD), sequence flow diagram (SFC) and structured text (ST) five languages ​​programming, easy to learn and use. 4 standard Modbus RTV communication protocol, can easily form a control network with the computer. 5 input and output port grouping design, can adapt to the use of different electrical properties. 6 easy to install, support for flat mounting and DIN rail mounting. 7 small size, light weight and low energy consumption. 8 cost-effective, used in cotton foreign fiber removal machine, can meet the needs of equipment, but also reduce design costs.

2. Equipment overview and system composition

The cotton foreign fiber removal machine is an automatic electronic device that can detect and eliminate harmful impurities in cotton online, integrating light, electricity and gas, and can be seamlessly connected to the pre-spinning process. The equipment mainly includes pre-stage cotton fan, beater motor, roller motor, suction cotton fan, light source system, high-speed camera, large-scale integrated processing board, industrial computer and high-speed gas valve, etc. Different, the requirements for power supply stability are different; the startup process is: first start the industrial computer, start the light source system after 20 seconds, start the suction cotton fan after the industrial computer starts, and then start the beater motor, after the beater speed is normal, Start the roller motor, start the front-end cotton fan, and finally start the camera and board, and finally the device automatically enters the running state. In addition, in the equipment installation and the production line of the textile factory, a unified power supply line and control center are used to start the entire production line and alarm. When the production line starts, the dust filter system is started first, then the post-stage carding equipment is started, then the foreign fiber removal machine is started, and the pre-stage opener is started, and the entire production line begins to produce cotton.

Based on the above process design requirements, the system uses PLC to start and stop logic control. The system consists of the PLC, intermediate relay, industrial computer, RS232 communication cable and the input and output switch of the foreign fiber removal machine of Nanda Alto CPU201-4002. The PLC is mainly responsible for receiving the opening signal of the production line and electrical logic for the cotton foreign fiber removal machine. Control, at the same time complete the light source life timing statistics, beater motor speed measurement and Modbus RTV communication with the industrial computer. The system hardware components are shown in Figure 1:

Figure 1 System composition

3, software function design

3.1 hardware configuration and port settings

Before the system design, according to its complexity, from the aspects of economy and reliability, NA-200PLC was selected as the control host of the cotton fiber removal machine control system. The PLC is powered by 220V AC. The main body has 24 digital input points (can be designed as source or sink input) and 16 digital relay output points. The CPU integrates two RS232 (Modbus RTV), 128K program storage space and 8K power-down keeps storage space, 4-channel high-speed single-phase counter. The specific PLC I / O allocation is shown in Figure 2.

Figure 2 PLC external I / O allocation

3.2 PLC internal resource allocation

In the process of designing the program, many intermediate relays, registers, timers and other devices are used. In order to facilitate programming and modification, the possible devices are listed before the program is written. Now, communication with the host computer and key components will be performed. The regulations are as shown in Table 1.