PLC Program for Heating and Mixing of Products

This is a PLC Program for Heating and Mixing of Products.

Material A and Material B are collected in a tank. These products are to be mixed and heated till it reaches set point temperature value. Implement automation of this system in PLC using Ladder Diagram programming language.

• To detect level of Material A and Material B, two separate level switches are used.
• And to detect low level, one more level switch is used at the bottom of the tank.
• These give output in digital terms that is when corresponding levels are detected.
• To control level of this system, Single Acting Piston valve can be used which has two states, either fully open or fully close.
• To control mixing, agitator is used which is connected with Motor shaft.
• Heater is installed inside the tank and temperature sensor such as RTD or Thermocouple is used to detect the temperature of liquid in the tank.
• This mixer is mixed until set point temperature is achieved.
• Outlet valve is then operated to drain the mixed product.

Here is PLC program for Heating and Mixing of Products, along with program explanation and run time test cases.

List of Inputs and Outputs
 I:1/14	= Start 				(Input)
 I:1/15	= Stop					(Input)
 B3:0/0	= Master Coil Bit			(Bit)
 I:1/0	= Level of Material B			(Input)
 I:1/1	= Level of Material A			(Input)
 I:1/2	= Low Level Switch (empty tank)		(Input)
 O:2/0	= Inlet Valve 1 (Material A Feed)	(Output)
 O:2/1	= Inlet Valve 2 (Material B Feed)	(Output)
 O:2/2	= Agitator Motor (Mixing)		(Output)
 O:2/3	= Heater				(Output)
 O:2/4	= Outlet valve to drain the product	(Output)

Ladder Diagram to heat and mix materials

• RUNG000 contain master start/stop with address of Start PB I:1/14 and Stop PB I:1/15.
• RUNG001 is to operate Inlet Valve of Material A with address O:2/0. It is operated when Low Level of the tank is detected by Level Low Switch I:1/2. And it is closed when Inlet Valve of material B starts that is when Level Material A is detected by a switch with address I:1/1. Start PB is also connected in parallel with the LLS, it is done so that when LLS or level of Material A is not detected, Inlet Valve is operated by Start PB.
• RUNG002 is to operate Inlet Valve of Material B with address O:2/1. It is opened when Material A is filled to its desired level (Level Material A). In other words, Valve of Material B is opened when Level of Material A is detected by I:1/1 and it is closed when Level of Material B is detected or Tank is full.
• RUNG003 operates Agitator Motor and Heater with address O:2/2 and O:2/3 respectively. When the tank is full with Material A and B, Level High (Level Material B) is detected. Agitator Motor is connected to the address O:2/2 and Heater to O:2/3. Agitator and Heater are run when I:1/0 is set to 1 that is when tank is full.
• RUNG004 is for Outlet Valve with address O:2/3. It is operated when the entire mixing and heating process is completed that is when temperature set point is reached. And this valve closed again is closed when LLS is again detected.

Inputs	                 Outputs	        Physical Elements
I:1/2 = 1	         O:2/0 = 1      	Open Inlet Valve 1
I:1/2 = 0 and I:1/1 = 0	 O:2/0 = 1      	Open Inlet Valve 1
I:1/1 = 1	         O:2/0 = 0	        Close Inlet Valve 1
I:1/1 = 1	         O:2/1 = 1      	Open Inlet valve 2
I:1/0 = 1	         O:2/1 = 0      	Close Inlet Valve 2
I:1/0 = 1	         O:2/2 = 1, O:2/3 = 1	Run Agitator Motor and Heater
Temperature ≥ 70°C	 O:2/2 = 0, O:2/3 = 0	Stop Agitator Motor and Heater
Temperature ≥ 70°C	 O:2/4 = 1      	Open Outlet Valve
I:1/2 = 1	         O:2/4 = 0      	Close Outlet Valve

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