This is a PLC Program to Drain Two Different Products from 2 Tanks.
There two different tanks which are to be operated. Draining of these two materials are controlled. Mixing in the ratio of 2:1 is to be done. Implement automation of this in PLC using Ladder Diagram programming language.
- Level gauge is used to measure level of the storage tank continuously
- Level gauge is connected with Level Transmitter which converts corresponding level output in 4-20mA equivalent.
- Analog I/O Modules are chosen to deal with Analog signals.
- Centrifugal pumps are used to drain material from both the tanks at the same time.
- Height of storage tank is 5meters that is 500cm and the level which is to be maintained is 470cm.
- Calculate necessary conversions and use registers to store data and to do arithmetic operations.
Here is PLC program to Drain Two Different Products from 2 Tanks, along with program explanation and run time test cases.
List of Inputs and Outputs I:1/14 = Start (Input) I:1/15 = Stop (Input) O:2/15 = Master Coil (Output) O:4 = Output to I-V converter of Pump1 (Output) O:6 = Output to I-V converter of Pump2 (Output) O:2/0 = Agitator to mix (Output) I:3 = Input to which transmitter is connected (Input) N7:0 = Register to store input data (Register) N7:1 = answer of division by value change per centimeter (Register) N7:2 = Multiplication answer (Register) N7:3 = Division to obtain 2:1 ratio (Register)
- RUNG001 comprises all the conversion needed to control pumps.
- Output of transmitter is in current signals which is 4-20mA.
- When output is 4mA, Analog Input Module converts it into 16bit equivalent hex numbers. Hence when input at I:3 to Analog module is 4mA, it moves 0000h into register and when 20mA, it moves FFFFh into register. Here register N7:0.
- Here height of the tank is 5m or 500cm. By converting it into equivalent hex, change in value per centimeter is 132.
- Value of N7:0 is then multiplied with 139 because when Level reaches 470cm, output is F0C0h. So when output at 470cm is multiplied with 139, we get full FFFFh at N7:2 to operate pump2 in full speed and the pump2 half the speed of pump1 to achieve 2:1 mixing ration.
- This multiplication is stored into N7:2 register. Digital to Analog conversion of value stored in N7:2 is performed inside the processor and equivalent mA current is received from terminal O:4 and O:6.
- Current to Voltage converter then converts current signals into voltage signal and adjusts motor speed.
- Agitator with output O:2/0 is activated as soon as the Master Start PB is pressed.
Inputs Outputs Physical Elements I:3 = F258h O:4 = O:6 = 0000h Pump1 and Pump2 are off I:3 = 792Ch O:4 = 8000h, O:6 = 4000h Pump1 = 4000RPM, Pump2 = 2000RPM I:3 = 50C8h O:4 = 5474h, O:6 = 2A3Ah Pump1 = 2640RPM, Pump2 = 1320RPM
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