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All I can tell you is a rough idea. If you want to do your paper homework, you need to understand it, and then add some usual structures and vocabulary.
Using MCGS to complete the liquid level control experiment of single tank PCL.
abstract
The system is a simulation test system that measures and controls the liquid level of the upper and lower water tanks, observes its change characteristics and studies the process control law in the process of simulating industrial production. The system structure is mainly composed of field sensors, PLC, upper computer and MCGS configuration software installed on the upper computer, which realizes simple control of the liquid level of the upper and lower water tanks.
First of all, the system structure should only be partially introduced.
The system is mainly composed of field sensors, PLC, PC and PC software.
1, PC screen and preliminary system structure
The interface structure of the upper computer is relatively simple, and the screen is mainly composed of two parts, the left part is the system structure schematic diagram \ display part, and the right part is the system state \ setting part.
The left part tells us that the whole system mainly includes: water storage tank, upper small water tank, water pump for supplying water from the water storage tank (pump frequency display), vortex flowmeter for measuring the flow of jellyfish pipe (no digital display), jellyfish pipe, valves on jellyfish pipe, overflow port of upper small water tank 1 (stateless feedback), liquid level of upper small water tank and drain valve 2. All valves have no valve feedback signal display. There is also a communication status indicator in the upper left corner of the screen to show the communication status between the upper computer and PLC.
The right part of the screen mainly has the following functions and displays:
Setting of proportional coefficient, integral and differential time.
Setting of set value SV
Field actual liquid level feedback value
Manually given output value OP
Historical curve and real-time curve corresponding to the liquid level and time of the upper and lower water tanks
Historical data query
Other function buttons: system exit, manual \ automatic switching, test help text.
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Second, the composition of the control signal
From the description of the system interface, there are mainly two field feedback signals.
1, the measured value of water tank liquid level is mainly realized by the liquid level sensor installed on the water tank. The signal is analog (4-20ma or voltage signal).
2. Frequency value of water pump motor
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System settings include:
1, and the setting unit of the highest water level is mm.
2, proportional coefficient integral time differential time
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Suggestions on the improvement of verb (verb abbreviation) system
1. Change the frequency measurement of water pump to the current measurement of water pump motor. On the one hand, the cost and reliability of current measurement are better than that of frequency measurement, and it is more scientific here. Current measurement can reflect three kinds of motor running states at the same time: motor health, motor working, motor starting and stopping.
2. Increase the feedback of the water supply valve 1 as the start interlock of the water supply motor, so that the motor cannot be started when the valve is closed.
3. Because the vortex flowmeter is set in the system, the signal can be fed back to the screen display, otherwise it will be wasted. The display of instantaneous flow can be increased. And increase the module of traffic accumulation. Only in this way can the function of the system be more perfect.
4. Add communication settings, mainly serial port settings. The serial number needs to be set in practical application.
5. It is suggested to replace S7-200 with Siemens LOGO. From the perspective of cost performance, the cost of Siemens LOGO is lower, and its function is enough to meet the current measurement and control needs.
-Buchong
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