====== CTD Box Function ======

**Count Down Counter**

Category: [[en-us_products:mpino_studio2:box_functions:counter|Counter Box Functions]]

===== Behavior =====

Preloads the current value with the set value, then decrements it once on each rising edge of the left condition. The done state turns ON at zero, where counting stops.

===== Syntax and Arguments =====

**Syntax:** ''CTD C12 3''

  * Target — counter memory C<n> (16-bit) or DC<n> (32-bit)
  * preset — starting count loaded on reset (an integer, not time)

===== Behavior Example =====

^ Run condition ^ Before ^ Command entered ^ Expected result ^
| Left condition ON | C12=3 | ''CTD C12 3'' | 3 rising edges → C12=0, C12 done contact=ON |

{{ :en-us_products:mpino_studio2:counter-ctd-timing.svg?1000 |CTD input, current value, and done state }}

===== Cautions =====

  * A counter changes once per rising edge of the left condition. On MPINO-8A4R(T)-S, C0 through C10 are mapped to board functions, so use C11 or later for a counter.

===== Box Functions in the Same Category =====

  * [[en-us_products:mpino_studio2:box_functions:counter:ctu|CTU View details]] — Count Up Counter
  * [[en-us_products:mpino_studio2:box_functions:counter:ctud|CTUD View details]] — Count Up/Down Counter