Which instruction type is specifically designed to process only once per program scan?

The One Shot Instruction (ONS) is specifically designed to execute once per program scan when the input condition is true. This means that when the input transitions from false to true, the ONS instruction outputs a true result for that scan cycle only, and it will not produce another true output until the input condition changes to false and back to true again in subsequent program scans.

This behavior is particularly useful in scenarios where a specific action needs to occur just once, such as triggering an event or state change without continuously retriggering as long as the input remains true. The ONS instruction ensures that the resulting output will only activate during the very first program scan where the input condition is met, preventing repetitive processing on subsequent scans.

The other options represent different types of instructions which have different purposes and behaviors. Continuous instructions are checked each cycle as long as the condition remains true, while single shot instructions are generally a variant designed to process based on a specific context. Latched output instructions maintain an output state until explicitly reset or changed, which is not the same as the one-time processing characteristic of the One Shot Instruction.