What type of instruction is required to reset the accumulated value of an RTO instruction?

The correct answer is RES because the RES instruction is specifically designed for resetting or clearing accumulated values in various instruction types, including the RTO (Retentive Timer On). In programmable logic controllers (PLCs), timers and counters accumulate values over time, and the RES instruction effectively returns these values back to zero, allowing for new timing or counting cycles to begin without the influence of previous data.

Using the RES instruction is vital in scenarios where a new timing event must start fresh, ensuring no residual values affect the operation. This clarity in function distinguishes the RES instruction as the appropriate choice when it comes to resetting timers or counters in programming environments for controller systems.

Understanding the function of reset instructions is crucial in programming logic as it helps maintain control over the operation of processes and automations by guaranteeing that no stale data remains in the system.