In the application of SCM, PLC control system has become an important part of its composition. Main microcontroller using PLC programming interface necessary to communicate using the LCD as the user interface, the interface can show operating state parameters of the PLC, the corresponding key can also be used to set specific parameters. PLC control system did get in microcontrollers widely used, but at the time of application, but also there will inevitably be problems of all kinds, especially where there are many sources of interference, seriously affected the ability of anti-jamming SCM PLC control system. Make the appropriate anti-jamming measures to accelerate the development of SCM has a crucial importance.
1 interfering factors affecting SCM PLC control system
interference factors that affect a lot of SCM PLC control system, the use of the process should be noted that in many aspects, only a combination of various factors influence, in order to better make the appropriate protective measures. The following specific interference analyzes on the main factors: distortion interference (1) of the power waveform. In the PLC control system is used more GRT, GTO power semiconductor devices and the like, these various semiconductor devices prone harmonic interference, noise at work, which is also the leading cause interference power waveform distortion. Further interference of a certain PLC control system. (2) a circuit coupled interference. Circuitry coupled interference occurs due to the common impedance circuit coupled to generate a current, the current number of naturally produced in the process have some interference with the PLC control system. The main cause is the choice of coupling PLC ground of improper or poor grounding caused. (3) contacts the input jitter interference components. In this process, the contact occurs mainly due to jitter occurring field strong vibration, it will produce an erroneous signal to form after shaking for interference contact occurs. (4) capacitive and inductive interference. Capacitive interference is caused due to the capacitance, there is a capacitive coupling between the source of interference and the interfering object, a capacitive coupling will interfere with the interaction of the PLC control system. While inductive coupling is due to the alternating magnetic field by means of a source of interference is the interference of the interference element is coupled inductively generated object. Either capacitive or inductive interference interference, interference generated by the PLC control system are not negligible.
2 Specific measures to strengthen the single chip PLC control system anti-jamming capability analysis
2.1 determine a reasonable hardware design programs to strengthen the system's anti-jamming capability
of hardware designed for the development of SCM has crucial significance. To a certain extent, the hardware design of some improvements, and propose measures for improvement, must be to strengthen the anti-jamming capability. When performing the improved hardware design, the need to pay attention to the following points: First, the sources of interference suppression, attenuation or cut off the transmission of electromagnetic interference, improve the ability of anti-jamming devices and systems, control systems for these three aspects of the anti-jamming the ability of crucial significance. Secondly, from the perspective of the hardware design reasonably configure the power supply, selection of effective measures performance equipment, proper grounding point, as grounding, etc., in every aspect of good control as possible, thereby improving the anti-system interference.
2.1.1 The use of fine system of anti-interference ability to strengthen the power
supply has the most direct link to the performance of the entire system. The use of fine power, power introduced can be effectively suppressed, there is a certain role in strengthening the system noise immunity. In conventional PLC control system, the most widely used power source is the power good barrier properties. Because the PLC control system itself has some anti-jamming capability, during use, the power supply and the power system wiring device separately, the benefits of doing so is to take full advantage of anti-jamming capability PLC control system, so as to enhance the anti-jamming system ability. However, if the system itself is a serious disruption, PLC control system itself using anti-interference ability is not enough, this time must be shielded isolation transformer powered, possibly together with the contact line filter under conditions permit is, interaction between the two, thereby suppressing the interference DC current generated in the system.
2.1.2 local conditions, establish the correct grounding system
to establish grounding system, the system can have anti-jamming capability to have the most direct impact. In practice, there are two main grounding purposes: one is to protect the security system; the other is to suppress the interference. Therefore, the main measures to improve anti-jamming capability of the grounding system is strengthened. System ground when using more ground there are three main ways: floating, directly to ground capacitance to ground. Face different realities, grounding will be used is not the same. In the PLC Control System in the most suitable way is directly grounded grounding. In contrast, direct ground is relatively simple to operate, the impact on performance is small, and the corresponding anti-interference ability is very strong, better adapted to the development of SCM PLC control system. The direct earthing is also divided into a series of different situations point grounding point grounding type and a parallel type. For more concentrated arrangement PLC control system is suitable for one-point access shunt, the center of each apparatus cabinet ground point to a separate ground lead wire grounding. If the spacing between the device is relatively large, suitable for serial access point type. Different situations, suitable for grounding methods will be different.
2.2 rational design software
in addition to the hardware system beyond a reasonable design, the software rational design is also essential. In the system, disruption varied, in order to eliminate interference from the fundamental hardware alone is absolutely impossible, and therefore at the same time strengthening the SCM PLC control system anti-jamming capability, the corresponding software for certain treatment for strengthen anti-jamming capability of the system has a great role in promoting.
2.2.1 Muting error signal may occur
faced with a complex electromagnetic environment, integrated hardware and software measures to eliminate interference measures in order to maximize the system. In the system, regularly produces a variety of reasons caused a lot of wrong signals, signals the presence of these errors will only further exacerbate the interference of the system. Make the appropriate improvements to the system software. With two internal timers, PLC control system is defined in only the sampling time of the switching signal is normal, this way, an error signal can be masked sent at other times. The main principle of this is that each time the operation of the device is fixed, the switching time of the signals is also fixed at the same time.
All hardware and software development system integrated experiment SCM experiment apparatus such as a CPU can complete 51/96/8088/8086 microcontroller, a microcomputer. On the basis of MCU Experimental system on. Increase in 8088 sixteen microcomputer principle and interface experiment. Integrated design, simply switch to a different CPU card, CPU can support a variety of experimental development. Two operating platform, can work independently, but also work online with the PC. Suitable for teaching "MSC-51 SCM principles and interface", "MSC-96 SCM principles and interface," "single-chip interface technology", "sixteen Microcomputer Principle and Interface" and so on. The MCS-51 / 96CPU card MCU Experimental system consisting of, in addition to experimental features, also has the function to develop simulation, the simulation may be 8031 / 32,87 / 89/51 / 52,89C1051 / 2051,80C196KB CPU, a simulation of the external space up to 64K. The purpose of the experiment guide book detailing each experiment, contents, list of wiring diagrams, block diagrams and diskette program interface, application development in microcontroller teaching researchers to use the experimental system according to their actual needs, can help users in the shortest time accurately and effectively complete the development and experimental tasks. Typical PLC control object section to simulate actual industrial process control, the entire implementation process demonstration PLC to verify the correctness of their own programming, master the practical application of PLC, and enhance students' interest in learning PLC. Products using hanging box, to facilitate project test development second extension and user.
Experimental item
(a), PLC programmable controller system Experiment:
1. AND, OR, NAND logic function Experiment 2. Timers, counters function test
3. Jump, branch function test 4. Experiment shift register
5. Experiment 6 The data processing function. Differential, bit manipulation experiments
7. Traffic lights PLC automatic control experiment 8. Stirrer PLC automatic control experiment
9. LED digital display PLC automatic control officer experiment 10. The four elevators PLC automatic control experiment
11. Machining center tool magazine 12 to select control experiment. Art style lantern PLC control experiments
13. Experiment automatic control of the motor 14. PLC control stepping motor
15. Experiment 16 analog TV transmitter tower. Loading automatic feeding system control experiment
17. Vending machine inspection 18. Automatic molding experiments
19. Experiment tower automatic water supply control system 20. Mail automatic sorting experiments
21. Control system simulation automatic washer 22. Plating Process Control
23. Shovel control programming training: set the PLC technology, computer control technology and integrated, that is the image of the model, there are vivid and specific operating mechanism, easy to test the operation is an ideal model institutions Programmable controller technology for physical experiments .
(II) Experimental system microcontroller:
the MCS-51 is single-chip test
software test
the external data memory expansion
experiment a clear routine
experimental procedures Chaizi two
third experiment spelling program
experimental data area of four transfer subroutine
Experiment 5 Experiment data sorting
sixth experiment to find the same number the number of
experimental seven-byte unsigned rapid multiplication routine
experiments over eight branch program
experiments nine pulse count (timer / counter experiment)
experiment ten computer clock (timer, interrupt comprehensive experimental device)
experiment eleven binary conversion to BCD
experimental twelve ASCII to binary conversion
experiment eight digital display thirteen
experimental fourteen experiments keyboard scan display
hardware experiment
from overlapping experiments suggest hardware circuit
test port P1 a lighting experiment
second experiment port P1 cornering light experiment
third experiment P3 .3 inputs, P1 port output
experiment 4 industrial sequence control (interrupt control)
experiment 5 8,255 square wave output the ABC
sixth experiment control 8255 PA PB port mouth
experiment 7 8255 traffic lights
experiment eight simple I / O port expansion experiment
experiment nine A / experiment D conversion
experiment ten D / A output square wave
test audio electronic eleven experiments twelve relay control
experiment thirteen Stepper motor experiment
8253 Experiment fourteen square wave
experiments fifteen parallel conversion experiments
Experiment sixteen external memory expansion Experiment
Experiment Experiment seventeen application serial port MCS-51 ㈠-- Duplex Communications
Experiment Experiment eighteen application MCS-51 serial port ㈡- - with PC
Communication
experiment nineteen closed-loop temperature control
Experiment twenty small DC motor speed control
experiments twenty-one external interrupt (emergency vehicles and traffic lights)
8088/8086 series of computer experiments
software test
experimental program cleared a
second experiment Chaizi program
third experiment spelling program
experiment 4 data areas mobile
experiment 5 data sorting experiments
sixth experiment to find a "zero" experiment 7 32-bit binary number multiplication
experiment over eight branch program
experiments nine display routines
experimental ten-key pad scan showed that the experimental
test eleven binary conversion to BCD
experimental twelve binary conversion to ASCII
Experimental hardware
from overlapping experiments suggest hardware circuit
experimental test (i) a parallel port 8255: ABC square wave output port
experiment two parallel port 8255 (ii) Experimental: PA PB port interface control
experiment three parallel port 8255 (iii) Experiment: traffic lights
Experiment 4 Simple I / O port expansion
experiment 5 A / D converter test
experiment six D / A conversion experiments (i): output square wave
experiment 7 D / A conversion experiments (i): output sawtooth
experiment experiment 8259 interrupt controller eight nine timer / counter: 8253 square wave
experiments ten relay control
experiment eleven 8251 serial communication experiment (i): spontaneous self-closing
experiment twelve 8251 serial communication experiment (ii): communication with the PC
experimental thirteen stepper motor control
experiment fourteen small DC motor speed control experiment
experimental fifteen closed-loop temperature control
experiment sixteen test audio driver
MCS-96 microcontroller test
software test
experimental program cleared a
second experiment Chaizi program
third experiment spelling program
Experiment 4 data transfer routines area
Experiment 5 data sorting experiments
sixth experiment to find the number of the same number
Experiment 7-byte unsigned rapid multiplication child program
experimental program branches over eight
experiment 1 experiment nine timer - the timer interrupt
experiments ten timers T1 and T2 simultaneously generate an interrupt
experiment 80C196 external interrupt eleven experimental
test method twelve software 80C196 interrupt
experiments using HSI thirteen pulse width measurement
experiment fourteen single pulse width measurement using HSI
experiment using HSO fifteen single pulse
experiment using sixteen consecutive pulses generated HSO
experimental seventeen software timer
experiment eighteen 80C196 a / D conversion experiments
experiment nineteen generate various waveforms using the PWM 80C196
experimental twenty binary conversion to decimal BCD to ASCII conversion
Experimental hardware
from overlapping experiments suggest hardware circuit
test port P1 a lighting experiment
Experiment two bending light port P1
third experiment P2.6 input, output port P1
Experiment 4 Industrial sequential control
Experiment 5 8255 ABC output square wave
experiments six port 8255 PA The PB control
experiment 7 8255 traffic lights
experimental eight simple I / O port expansion experiment
experiment nine A / D conversion experiments
experiment ten D / A output square-wave experiments eleven relay control
experiments twelve 8253 square-wave
experiments thirteen serial 80C196 interface on the
experiment fourteen seven-segment LED digital display test
experimental fifteen keyboard display comprehensive experimental
test sixteen audio drivers test
test test seventeen stepper motor
experiment eighteen DC motor
experiment nineteen external interrupt (emergency vehicles and traffic lights)
