I. Introduction With the continuous development of science and technology, a variety of control techniques applied to agricultural fields, in order to achieve the automation of agricultural production. Since agricultural operations are carried out in the field, a great work environment free from outside influence, so the application of agricultural operations control system must have good anti-jamming performance, shockproof performance and simple operation, use and maintenance more convenient. For these reasons, this paper proposes to use air-launched programmable controller to control the types of drill seeding process. Programmable controller is a digital computing operation of electronic systems Has a strong anti-interference ability and wide adaptability. The programming language is easy to learn, easy maintenance and small amount of work. Application of PLC to control the gas fire drill seeding process, enabling the planting of automation, E6 body acceleration on the seed. At this point, the gas pressure rapidly reduced to atmospheric pressure; seeds obtained in the accelerating tube speed, the effect of the kinetic energy injected into the depth of soil is expected to complete the planting. Seeding device mainly for traction control solenoid valve, Stepper motor, 2 2 solenoid valve power, Delay and breakpoint control. PLC controller for the internal movement of seed in the planter s control, that is the seed from the kind of box into the seed tube, Shoot from the seed tube into the cavity of the control species; the same time, gas from the two second solenoid valve control chamber into the shooting kind. 3, PLC control system hardware configuration n ; mso-hansi-font-family: Times New Roman "> under the control of the seeding system control device requirements analysis, the input signal with the system open button and stop button signal; output signals from the kind of seed box into the seed tube, Seeds from the species of seed tube into the launch chamber and the gas from the two two types of solenoid valve into the fire chamber. The seed planter of the control input, Less than the output signal, input 2 points, output points to 3, the required I / O points are small, is a small stand-alone control system, so choose low-end machine can be small in general. Left margin of its capacity to choose the
Mitsubishi F1-12MR PLC as a controller-based control systems constitute the planter, the host of I / O points for the 6 / 6 Table 1 is the PLC s input, Output allocation table. 4, PLC control system software design Specific control process are: system initialization, press the start button X000, stepper motors, and electric traction electromagnets may also work; seeds from the kinds of containers into the seed tube, solenoid valve will be launched at the same time kind of traction the top of the seed cavity valve pressure, seeds from the seed tube for gravity glide on their own metering valve into the shooting types of cavity on the surface, time delay relay T0 began to work; at this time normally closed switches T0, Y000 and Y001 e = "font-family: Arial; mso-ascii-font-family: Times New Roman ; mso-hansi-font-family: Times New Roman "> disconnect, to ensure that two two-pass solenoid valve Y002 in the non-working state. T0 work after 5 s stepper motor Y000 and Y001 traction power solenoid valve, T0 stop working; time normally closed switches T0, Y000 and Y001 to restore closed state, two second solenoid valve Y002 was electric, gas from the valve into the fire kind of cavity, the time delay relay T2 have to call work, working conditions continued to 2 s. Meanwhile, the seeds are pressed into the high-pressure gas acceleration tube Roman "> was accelerated in the accelerating tube, then launched into the soil, to complete a shot kind of process, then enter the next planting. If you are finished planting operation, simply press the stop button X001 can make planter to stop working. This ladder with a self-locking feature, press the start button X000, only in the stepper motor and the traction valve Y001 Y000 power after two second solenoid valve Y002 to get electricity working. The aim is to ensure that only the species in fire When the seed cavity in two before the second solenoid valve work, the gas can into the fire kind of cavity, to prevent the broadcast air kind of phenomenon. When you press the stop button X001, all components are stopped. : # 339966; font-family: Arial; mso-ascii-font-family: Times New Roman ; mso-hansi-font-family: Times New Roman "> 5, PLC control system for the maintenance of planting PLC did not lead to shortened life expectancy within the easy-wear components, so the reliability is high, but should also do regular routine maintenance and repair work. As the controller is working in the field, the environment is rather poor, should be based on the specific situation at any time for controller maintenance. (1) Check whether the environment meets the requirements Control of the seeding system is based on PLC, although a strong anti-interference ability, in order to ensure the control system work properly, Extend the service life of control, seeding the environment should be as far as possible consistent with PLC nsi-font-family: Times New Roman "> ???. usually in the spring sowing work, operating temperature in this range, to meet the requirements; to ensure the slack season, ambient temperature storage planter not in this temperature range , the temperature is too high or too low will shorten the life of PLC controller. (2) In the course of work and transport, avoid strong vibrations and shocks In the case of vibration and shock, will become the PLC unit is not firmly fixed, external wiring bolts loose, I / O module terminal becomes not fastened, and even cause damage PLC. nt: 21.1pt; mso-para-margin-bottom: 1.0gd; mso-char-indent-count: 2.0 "> (3) Check the power supply Direct impact on the quality of power supply to the controller PLC, reliability, failure rate is higher parts. Check the voltage is not required to meet the rated range, the voltage fluctuations are too frequent. Frequent voltage fluctuations will speed up the aging of electronic components, module voltage, regulated power supply should be installed. (4) Check the PLC program memory in the battery PLC program at any time check the battery memory usage, less power consumption should be timely replacement of the battery. mily: Times New Roman "> (5) Check whether the sound output contacts contacts General output electric shock device for frequent moves, some prone to loose their contacts, so that output contact connection is bad. (6) the timely replacement of the internal lithium battery PLC PLC internal lithium battery life is generally 3 years, should always pay attention to “ BATT. V ” LED indicator of the state, in a timely manner a new battery. VI Conclusion > The system will be field programmable controllers used in agricultural planting, and the system still has some of the extensions. Pneumatic seeding technology with the continuous development of its control system should be carried out with the improved functionality of the system s expansion will help seeding technology, opening up a new planting area. PLC control system, easy maintenance, low cost technology, used in the agricultural sector has great economic and social benefits.