Nexto Xpress - Using the CTUD Counter

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Functional block that acts as an incrementer and decrementer. 

INPUTS

CU : BOOL; if a rising edge occurs at this input, the counter value (CV) is incremented by 1 until it reaches PV. 

CD : BOOL; if a rising edge occurs at this input, the counter value (CV) is decremented by 1 until it reaches 0. 

RESET : BOOL; if TRUE, CV will be reset to zero.

LOAD : BOOL; if TRUE, it will be set to the value of PV.

PV : WORD; upper limit for incrementing or decrementing CV.

ATTENTION: The WORD data type, used for PV in MasterTool IEC XE, does not correspond to the IEC standard, which specifies the INT data type for this. 

OUTPUTS

QU : BOOL; returns TRUE when CV is incremented to a value >= PV.

QD : BOOL; returns TRUE when CV is decremented to 0.

CV : WORD; contains the value to be incremented or decremented; will be initialized to 0 if RESET is TRUE; will be increased by 1 whenever there is a rising edge from FALSE to TRUE on CU; will be decreased by 1 whenever there is a falling edge from TRUE to FALSE on CD, as long as the value is not less than 0.