Logix5000 Controllers General Instructions - SLAC Confluence

Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) 103ConditionprescanRelay Ladder ActionThe .EN, .TT, and .DN bits are cleared.The .ACC value is set to equal the .PRE value.The rung-condition-out is set to false.rung-condition-in is falseexamine .DN bit.DN bit = 0.DN bit = 1examine .EN bit.EN bit = 1.EN bit is cleared.TT bit is set.EN bit = 0.TT bit is set.ACC = .ACC + (current_time - last_time)examine .ACC.ACC < .PRE.ACC ≥ .PRE.DN is cleared.TT bit is cleared.ACC valuerolls overnoyesrung-condition-out is set tofalse.ACC = 2,147,483,647endrung-condition-in is trueThe .EN, .TT, and .DN bits are set.The .ACC value is cleared.postscanThe rung-condition-out is set to true.The rung-condition-out is set to false.Publication 1756-RM003I-EN-P - January 2007