CTD down counter symbol
Also called CTD, Count down counter
A down counter: LD loads the preset PV into the count CV, each rising edge on CD takes one off, and Q goes true when CV reaches zero.
IEC 61131-3What the CTD down counter symbol means
A down counter: LD loads the preset PV into the count CV, each rising edge on CD takes one off, and Q goes true when CV reaches zero.
How it is drawn
IEC 61131-3 ladder diagram
CTD function block. A box marked CTD with inputs CD, LD and PV and outputs Q and CV.
LD SVGWhere you see it
Counting down a batch or a number of remaining cycles.
Related symbols
Frequently asked questions
What does the CTD down counter symbol look like?
A box marked CTD with inputs CD, LD and PV and outputs Q and CV.
Where is a CTD down counter used?
Counting down a batch or a number of remaining cycles.
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