PLC Timer Calculator (TON / TOF / RTO)

Calculate PLC timer values for TON (Timer On Delay), TOF (Timer Off Delay), and RTO (Retentive Timer On). Essential for industrial automation programming.

PLC Timer Configuration

Timer Type

Preset Time (PT)

Input State

Elapsed Time (ET)

PLC Scan Time (Optional)

PLC Timer Types Explained

TON (Timer On Delay)

Starts counting when input goes ON. Output turns ON after preset time expires. Resets when input goes OFF.

TOF (Timer Off Delay)

Output turns ON immediately when input goes ON. Starts counting when input goes OFF. Output turns OFF after preset time expires.

RTO (Retentive Timer On)

Accumulates time when input is ON. Continues counting even if input goes OFF. Requires explicit reset to clear accumulated time.