What operation does the SUB instruction perform when energized?

The SUB instruction is specifically designed to perform subtraction in a programmable controller system. When the SUB instruction is energized, it takes two operands—Source A and Source B. The operation then subtracts the value contained in Source B from the value in Source A. This operation results in the difference being stored in a designated destination.

The understanding of this instruction is fundamental as it reflects the basic arithmetic operations that programmable controllers are capable of executing. In various applications, this capability is crucial for tasks that require mathematical calculations, such as determining offsets, calculating remaining quantities, or adjusting process parameters based on input values.

It's important to note that while other choices may involve operations related to addition, copying, or comparison, these do not accurately describe the specific function of the SUB instruction, which is focused solely on performing subtraction. This clarity ensures that programmers can effectively utilize this instruction within the logical flow of their control strategies.