Subtraction of two operands using subtract instruction in the PLC.

Subtraction of two operands using subtract instruction in the PLC.

Application:-Explain subtraction instruction in the PLC. Write PLC program for explanation using ladder diagram language.

Components:-Programmable logic controller, HMI panel, Ethernet cable, 24 V DC power source.

Diagram:-

Explanation:-

The subtraction instruction is used for subtraction of two values for any data records. For example, we want two subtract one value from the second value in the application like weight 1 and weight 2 and we want to show the subtraction of two weight like we want to subtract weight 1 from weight 2 and show on the HMI.

So for that, we have two take two input field in the HMI system and make weight 1 input field and weight 2 input field so the user can enter a value in the input field. And also users can monitor subtraction value in the result field.

PLC program:-

Write the ladder program for subtraction instruction using ladder diagram language. Here for ladder logic, we can use any supported PLC a system like S7-1200, S7-1500 or any other PLC which can support this instruction. In our application, we have used S7-1200 PLC for reference.

M Memory:-

Weight 1:-MW10

Weight 2:-MW12

Actual value:-MW14

PLC program Explanation:-

In-network 1 we have taken subtraction instruction for the subtraction of two weights. Weight 1(MW10) will be entered from the HMI and weight 2 (MW12) will be entered from the HMI. Instruction is executed and generates output in the MW 14 word.