Logix5000 Controllers General Instructions - SLAC Confluence

Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) 119Input Parameter Data Type DescriptionDN BOOL Timing done output. Indicates when accumulated time is greater than or equal to preset.Status DINT Status of the function block.InstructFault (Status.0) BOOL The instruction detected one of the following execution errors. This is not a minor or majorcontroller error. Check the remaining status bits to determine what occurred.PresetInv (Status.1) BOOL The preset value is invalid.Description:The RTOR instruction accumulates time until it is disabled. When theRTOR instruction is disabled, it retains its ACC value. You must clearthe .ACC value using the Reset input.The time base is always 1 msec. For example, for a 2-second timer,enter 2000 for the PRE value.TimerEnableenable bit (EN)Resettimer timing bit (TT)timer done bit (DN)presettimer accumulated value (ACC)0timer did not reach PRE value16651Set the Reset input parameter to reset the instruction. If TimerEnable isset when Reset is set, the RTOR instruction begins timing again whenReset is cleared.How a Timer RunsA timer runs by subtracting the time of its last scan from the time now:ACC = ACC + (current_time - last_time_scanned)Publication 1756-RM003I-EN-P - January 2007