From the course: Learning PLC Ladder Logic: 2 Diving Deeper

Introduction to math instructions - Ladder Logic Tutorial

From the course: Learning PLC Ladder Logic: 2 Diving Deeper

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Introduction to math instructions

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- [Instructor] Math instructions are one of the common instructions used in PLC. They are used within the program to perform mathematical operations on values stored in memory words or registers. All math instructions have a similar layout. They are block instructions with two sources and one destination. Math instructions are output instructions, so we add them to the right hand side of the rung. They all work the same way. The calculation is done as destination equals source A and whatever operation is selected and then source B. So they use the content of two words or registers and perform the desired operation. The source values are simply read only, we don't change them, and the destination values are changed according to the operation used. Math instructions operation can be conditional and unconditional. With conditional arithmatic instruction, the input logic determines when the instruction executes and for unconditional, the instruction executes with every scan.

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