What is true about a MOV instruction?

The MOV instruction in a programming environment such as Rockwell ControlLogix is used to transfer data from a source to a destination. The correct statement about the MOV instruction is that the source value remains unchanged after execution. This is fundamental to the MOV operation, as it ensures that the original data at the source address can be preserved and used elsewhere without alteration.

In practical applications, this characteristic is critical when programming, as you often need to maintain the integrity of the source data while manipulating or storing it in different places. The MOV instruction simply copies the data rather than modifying it, which allows for safe transfer and clear logic flow in your programming.

In contrast, the other statements present scenarios or implications that do not align with how the MOV instruction functions. For example, the idea that the source value changes after execution directly contradicts the purpose of the MOV instruction. Additionally, the notion that the destination value is manipulated directly implies a different kind of operation that could lead to confusion, as the instruction copies data rather than manipulates it in place. Finally, stating that the destination value is always set to zero does not correctly describe the operation; the destination receives the value of the source, which could be any valid data, not just zero.