This is PLC Program for automatic heating and mixing of products.

Problem Description

Make an automatic system in which two materials are collected in one tank. All materials are to be mixed till it achieves predefined set point of temperature.

Make a ladder program in S7-1200 PLC for this application.

Problem Diagram

Problem Solution

• We can solve this problem by using simple logic. For this system consider two separate level switches to detect the level of two different materials (Lets say Material A & Material B). Also consider one level switch for empty level detection.
• For controlling the level we can use single acting valve (fully open and fully close type).
• For mixing, agitator is used and it is connected with motor shaft.
• Heater and temperature sensor are installed inside the tank.
• Here materials are mixed until it reaches the set point of temperature and after mixing, outlet valve (Q0.4) will be operated to drain the mixed products.

Program

Here is PLC program for automatic heating and mixing of product.

List of Inputs/Outputs

Inputs List:-

• Cycle START:-I0.0
• Cycle STOP:-I0.1
• Level of material B:-I0.2
• Level of material A:-I0.3
• Empty level switch:-I0.4
• Temperature sensor:-I0.5

Outputs List:-

• Inlet valve 1:-Q0.0
• Inlet valve 2:-Q0.1
• Agitator motor:-Q0.2
• Heater:-Q0.3
• Outlet valve:-Q0.4

M Memory:-

• M0.0=Cycle ON

Ladder diagram for automatic heating and mixing of product

Program Description

In this problem we will consider S7-1200 PLC and TIA portal software for programming.

Network 1:- This network shows simple latching circuit for cycle ON and cycle OFF. Normally Open (NO) contact of cycle START button (I0.0) and NC contact of cycle STOP button (I0.1) for cycle activation.

Network 2:- This network is to operate Inlet Valve 1(Q0.0). It is operated when Low Level of the tank is detected (I0.4). And it is closed when Level Material A is detected by a switch with address (I0.3). START PB (I0.0) also connected in parallel so if low level not detected, inlet valve can be started by pressing START PB (I0.0).

Network 3:- This network is to operate inlet valve 2 (Q0.2).It is operated when material A is filled with its desired level. When cycle is running and level of material A is detected, inlet valve 2 (Q0.1) will be ON.

Network 4:- This network is to operate agitator motor and heater. When tank is full with material A and material B, heater (Q0.3) and agitator motor (Q0.2) will be ON.

Network 5:- When entire mixing process and heating are completed, outlet valve (Q0.4) will be ON. NC contact of empty level switch (I0.4) is used to stop the outlet valve when tank is empty.

Note: – Above logic is for explanation of certain application only. The diagram is for representation purpose, actual system might be different form this system.

Runtime Test Cases

Author : Bhavesh

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