Short summary

Name	`CTD_UDINT`
→POU type	→function block
Category	IEC-block, Counter
Conform to →IEC-standard	no restrictions
Graphical interface
Available since	version 1.19.0 (for logi.CAD 3)

Functionality

The block is a down-counter (for UDINT values).

If there is a positive →edge at input CD, the counter is activated and decrements the counter value by 1. If input LD is →turned on, the counter value is reset to the initial value entered at PV. If the counter value reaches or falls below 0, output Q is set to value TRUE (or an equivalent). The decrementing is stopped, if the lower limit of UDINT (= value -0) is reached. Output CV returns the current counter value of the block.

In-/outputs

	Identifier	→Data type	Description
Inputs:	`CD`	`BOOL`	decrement in case of positive edge
	`LD`	`BOOL`	flag for reset to value of `PV`
	`PV`	`UDINT`	initial value for counting
Outputs:	`Q`	`BOOL`	flag showing whether value `0` is reached or not
Outputs:	`CV`	`UDINT`	current counter value

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

Example for usage within ST-editor

PROGRAM Test
    VAR
        myCTD          : CTD_UDINT;
        StartCounter   : BOOL;
        RestartCounter : BOOL;
        out            : BOOL;
        counter        : UDINT;
    END_VAR
 
    myCTD(CD := StartCounter, LD := RestartCounter, PV := 10, Q => out, CV => counter);
    (* Instance of block 'CTD_UDINT' is called: The counter is activated, when 'StartCounter' is 'TRUE'. The value for counting is reset to '10', when 'RestartCounter' is 'TRUE'. *)
    (* Appropriate variables access the outputs. *)
END_PROGRAM

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.