PLC Timing Counting in 2026: IEC 61131-3 TON, HSC & Conveyor Ladder
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PLC Timing Counting in 2026: IEC 61131-3 TON, HSC & Conveyor Ladder
Timing and counting remain the two most-deployed PLC instructions on every conveyor, filler, and bottling line on the planet. This 2026 rewrite updates the original 2024 case study with current IEC 61131-3 function block conventions, high-speed counter (HSC) wiring on modern CPUs, and a ladder diagram you can drop straight into Studio 5000, TIA Portal, or GX Works3.
Detail
TP / TON / TOF timers and CTU / CTD counters are IEC 61131-3 standard blocks, not vendor-locked.
Conveyor timing case: photo-eye starts TON, preset in ms, output stops the VFD after the dwell.
High-speed counters (HSC) exceed the normal scan rate, essential for encoder feedback above 1 kHz.
Since 2024: OPC UA Pub/Sub over TSN has joined HSC and timers as the third leg of modern timing-control design.
Cross-vendor ladder is portable: same logic, three different programming environments, identical outcome.
Timing and counting are still the workhorse instructions on any PLC line, and modern IEC 61131-3 timers and high-speed counters make them faster, safer, and more portable across Siemens, AB, and Mitsubishi platforms than in 2024.
The original 2024 version of this article framed timing counting as "trigger an event after a specific time interval." That is still true, but two things have changed:
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