Logix5000 Controllers General Instructions - SLAC Confluence

Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) 123Count Up (CTU)The CTU instruction counts upward.This instruction is available in structured text and function block asCTUD, see page 131.Operands:Relay LadderOperand Type Format DescriptionCounter COUNTER tag counter structurePreset DINT immediate how high to countAccum DINT immediate number of times the counter has countedinitial value is typically 0COUNTER StructureMnemonic Data Type Description.CU BOOL The count up enable bit indicates that the CTU instruction is enabled..DN BOOL The done bit indicates that .ACC ≥ .PRE..OV BOOL The overflow bit indicates that the counter exceeded the upper limit of 2,147,483,647. Thecounter then rolls over to -2,147,483,648 and begins counting up again..UN BOOL The underflow bit indicates that the counter exceeded the lower limit of -2,147,483,648. Thecounter then rolls over to 2,147,483,647 and begins counting down again..PRE DINT The preset value specifies the value which the accumulated value must reach before theinstruction sets the .DN bit..ACC DINT The accumulated value specifies the number of transitions the instruction has counted.Publication 1756-RM003I-EN-P - January 2007