Logix5000 Controllers General Instructions - SLAC Confluence

Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) 131Count Up/Down (CTUD)The CTUD instruction counts up by one when CUEnable transitionsfrom clear to set. The instruction counts down by one when CDEnabletransitions from clear to set.This instruction is available in relay ladder as three separateinstructions: CTU (see page 4-123), CTD (see page 4-127), and RES(see page 136).Operands:CTUD(CTUD_tag);Structured TextVariable Type Format DescriptionCTUD tag FBD_COUNTER structure CTUD structureFunction BlockOperand Type Format DescriptionCTUD tag FBD_COUNTER structure CTUD structureFBD_COUNTER StructureInput Parameter Data Type DescriptionEnableIn BOOL Function Block:If cleared, the instruction does not execute and outputs are not updated.If set, the instruction executes.Default is set.Structured Text:No effect. The instruction executes.CUEnable BOOL Enable up count. When input toggles from clear to set, accumulator counts up by one.Default is cleared.Publication 1756-RM003I-EN-P - January 2007