 Countup and Countdown instructions are used to count rung transitions. The Countup instruction, or CTU, is used to count false to true rung transitions. When rung conditions for a CTU instruction have made a false to true transition, the Countup Enable bit is energized and the accumulated value is incremented by one count. After the accumulated value reaches the preset value, the counter instruction done control bit is enabled. The accumulated count is retained until cleared by the reset instruction addressed same as the counter file. The Countdown instruction, or CTD, works the opposite way of the CTU by counting true to false rung transitions. When rung conditions for a CTD instruction have made a true to false transition, the Countdown Enable bit is energized and the accumulated value is decremented by one count. After the accumulated value reaches the preset value, the counter instruction done, or DN control bit, is enabled. The accumulated count is retained until cleared by the reset instruction addressed same as the CTU file. Pairing a CTU and CTD in a counting sequence using the same counter file is demonstrated in a parking garage application. As vehicles enter the parking garage, PB1 is pressed to open the gate. The CTU instruction increments by one and the visual display is updated. Cars exit the garage by pressing PB2 to open the gate. The CTD instruction is decremented by one and the visual display is updated. With both the up and down counters addressed to the same counter file, the preset and accumulated values are the same. When the accumulated value reaches the preset value, the counter done bit enables output C and full is displayed. Both counters are reset using the reset or RES control bit addressed the same as the counter file.