Logix5000 Controllers General Instructions - SLAC Confluence

Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) 105Retentive Timer On (RTO)The RTO instruction is a retentive timer that accumulates time whenthe instruction is enabled.This instruction is available in structured text and function block asRTOR, see page 118.Operands:Relay LadderOperand Type Format DescriptionTimer TIMER tag timer structurePreset DINT immediate how long to delay (accumulate time)Accum DINT immediate number of msec the timer has countedinitial value is typically 0TIMER StructureMnemonic Data Type Description.EN BOOL The enable bit indicates that the RTO instruction is enabled..TT BOOL The timing bit indicates that a timing operation is in process.DN BOOL The done bit indicates that .ACC ≥ .PRE..PRE DINT The preset value specifies the value (1 msec units) which the accumulated value must reachbefore the instruction sets the .DN bit..ACC DINT The accumulated value specifies the number of milliseconds that have elapsed since the RTOinstruction was enabled.Description:The RTO instruction accumulates time until it is disabled. When theRTO instruction is disabled, it retains its .ACC value. You must clearthe .ACC value, typically with a RES instruction referencing the sameTIMER structure.Publication 1756-RM003I-EN-P - January 2007