Understanding of the program structure and programming methods, based on the actual preparation of the PLC program. PLC control system design needs to go through the following process.
(A) analysis of the controlled object and put forward the control requirements
Detailed analysis of the process and characteristics of the controlled object to understand the controlled object machine, electricity, liquid between the proposed control of the PLC object to be controlled by the control system requirements, to determine the control program, to develop the design task book.
(B) determine the input / output device
According to the control requirements of the system, all input devices (such as buttons, position switches, change-over switches and various sensors) and output devices (such as contactors , solenoids, signal lamps and other actuators Etc.) to determine the input / output devices associated with the PLC to determine the PLC's I / O points.
(C) choose PLC
PLC selection includes PLC model, capacity, I / O modules, power supply, etc., see Section II of this chapter.
(D) distribution of I / O points and design PLC peripheral hardware lines
1. Assign I / O points
Plot the PLC's I / O points and input / output device connection diagram or correspondence table, this section can also be carried out in step 2.
2. Design PLC peripheral hardware line
Draw the electrical circuit diagram of the rest of the system, including the main circuit and the control circuit that did not enter the programmable controller .
The PLC's I / O connection diagram and PLC peripheral electrical circuit diagram composed of the system electrical schematic diagram. So far the system hardware electrical circuit has been identified.
(E) programming
Program design
According to the system's control requirements, using the appropriate design method to design PLC program. Procedures to meet the system control requirements of the main line, one by one to write to achieve the various control functions or sub-tasks of the program, and gradually improve the system specified functions. In addition, the program should usually include the following:
(1) initialize the program. After the PLC is powered on, generally have to do some initial operation, to make the necessary preparations for the start, to avoid system malfunction. The main contents of the initialization process are: some of the data area, counters, etc. cleared, the data needed to restore some of the data area, set or reset some of the relay , for some initial state display and so on.
(2) testing, fault diagnosis and display procedures. These programs are relatively independent, and are generally added when the programming is basically completed.
(3) Protection and chain program. Protection and chain is an integral part of the program and must be carefully considered. It avoids confusion in the control logic caused by illegal operations.
2. Program simulation debugging
The basic idea of ​​program simulation debugging is to simulate the actual state of the scene in a convenient form and create the necessary environmental conditions for the operation of the program. According to the different ways of generating field signals, there are two forms of simulation: hardware simulation and software simulation.
(1) The hardware simulation method is to use some hardware devices (such as another PLC or some input devices, etc.) to simulate the scene generated by the signal, and these signals are hardwired to the input of the PLC system, the timeliness Strong.
(2) Software simulation method is to write another set of simulation program in PLC, simulate to provide on-the-spot signal, which is simple and easy to implement, but the timeliness is not easy to guarantee. Analog debugging process, the method can be used sub-debugging, and use the programmer's monitoring capabilities.
(F) hardware implementation
Hardware implementation is mainly the control cabinet (Taiwan) and other hardware design and on-site construction. The main contents are:
1) Design control cabinets and console parts and other parts of the electrical layout and installation wiring diagram.
2) Design the electrical interconnection between various parts of the system.
3) According to the construction drawings on-site wiring, and conduct a detailed inspection.
Because programming and hardware implementation can be carried out simultaneously, the design cycle of PLC control system can be greatly shortened.
(Seven) online debugging
Online debugging is to simulate the debugging process to further online tuning. Online debugging process should be gradual, only from the PLC input device, and then connect the output device, then connect to the actual load and other debugging step by step. If does not meet the requirements, the hardware and procedures to make adjustments. Usually only need to modify some programs.
After all debugging, delivery test run. After a period of operation, if the work is normal, the program does not need to be modified, the program should be cured to the EPROM, in case the program is lost.
(Vi) organize and prepare technical documents
Technical documents include design specifications, hardware schematics, installation wiring diagram, electrical components list, PLC program and manual.
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Speed:=1.0m/s
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Temperature: -35`90℃
Speed:=0.5m/s
Pressure:≤40mpa
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Material:PTFE+NBR
Temperature:-40~110℃
Speed:=1.0m/s
Pressure:≤40mpa
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Material:Polyurethane+modified polyoxymethylene
Temperature: -35~110℃
Speed:=1.0m/s
Pressure:≤50mpa
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Material:Polyurethane
Temperature:-35~100℃
Speed:=1.0m/s
Pressure:≤40mpa
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Temperature:-40~110℃
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Material:polyurethane
Temperature: -35~110℃
Speed:=0.5m/s
Pressure:≤50mpa
SPG piston combination seal
Temperature:
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Speed:=0.3m/s
Pressure:≤70mpa
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Material
NBR+Polyurethane + Modified PolyoxymethyleneTemperature:-35`110℃
Speed:=0.3m/s
Pressure:≤70mpa
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Material
Polyester rubberTemperature:-40`100℃
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Temperature:-35~110℃
Speed:=0.5m/s
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