Logix5000 Controllers General Instructions - SLAC Confluence

100 Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES)Timer Off Delay (TOF)The TOF instruction is a non-retentive timer that accumulates timewhen the instruction is enabled (rung-condition-in is false).This instruction is available in structured text and function block asTOFR, see page 114.Operands:Relay LadderOperand Type Format DescriptionTimer TIMER tag timer structurePreset DINT immediate how long to delay (accumulate time)Accum DINT immediate total msec the timer has countedinitial value is typically 0TIMER StructureMnemonic Data Type Description.EN BOOL The enable bit indicates that the TOF instruction is enabled..TT BOOL The timing bit indicates that a timing operation is in process.DN BOOL The done bit is cleared when .ACC ≥ .PRE..PRE DINT The preset value specifies the value (1 msec units) which the accumulated value must reachbefore the instruction clears the .DN bit..ACC DINT The accumulated value specifies the number of milliseconds that have elapsed since the TOFinstruction was enabled.Description:The TOF instruction accumulates time until:• the TOF instruction is disabled• the .ACC ≥ .PREThe time base is always 1 msec. For example, for a 2-second timer,enter 2000 for the .PRE value.Publication 1756-RM003I-EN-P - January 2007