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ctu ctd

1 article tagged “ctu ctd”.

Flat vector diagram comparing a CTU count-up and CTD count-down PLC counter instruction side by side with accumulated value bars and ladder rung connections
plc countersctu ctdladder logic

CTU vs CTD: PLC Counter Instructions Compared

CTU counts up from zero; CTD counts down from a preset. Learn when to use each, how they differ across platforms, and how to wire both into working ladder logic.

Aug 2, 2026 · 9 min read

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