PLC Timer and Counter Calculator

Formula

• Preset time (s) = PV × time base / 1000
• TON: Q = 1 when ACC ≥ PV and enabled
• CTU: CV increments on CU; Q = 1 when CV ≥ PV

About this calculator

Part of our Manufacturing Calculators collection. Welding, stamping, punch and die tooling, 3D printing, material weight, and production automation.

How it works

Set timer or counter mode and enter preset, accumulated, and enable values. The calculator shows output Q and updated accumulator or count for common PLC instruction blocks. Use this to sanity-check ladder logic timing and counting behavior.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Worked example

TON timer: PV=100, ACC=50, time base 10 ms, enabled.

1. Preset = 100 × 10 / 1000 = 1.0 s
2. Elapsed = 0.5 s
3. ACC < PV → Q = 0 (not timed out yet)

Result: Output off, 0.5 s elapsed of 1.0 s preset.

When to use

• Sanity-checking PLC timer preset vs accumulated values
• Verifying counter preset and output Q logic
• Teaching TON, TOF, TP and CTU, CTD, CTUD behavior

Limitations

• Single-scan simulation; not a cycle-accurate PLC emulator
• Time base must match your PLC instruction (e.g. 10 ms, 100 ms)
• Does not model retentive timers or one-shot edge detection

FAQ

What is TON?

Timer on-delay: output Q turns on after the preset time while the input remains enabled. ACC resets when input goes off.