What is the main function of the subtract instruction?

The main function of the subtract instruction in a programmable controller or programming context is to take one numerical value and deduct it from another. This operation results in the difference between the two values, which is essential for various calculations and logical operations within control systems.

Subtracting one value from another is a fundamental operation used in programming and control logic, enabling tasks such as adjusting numerical parameters, calculating changes in signals, or determining the difference between setpoints and actual measurements. This instruction is integral to performing arithmetic operations that underpin more complex functions and processes in programmable controllers.

Other options involve different arithmetic operations—comparing values, adding, or dividing—which do not relate directly to the purpose of the subtract instruction focused specifically on removing one value from another.