Logix5000 Controllers General Instructions - SLAC Confluence

Bit Instructions (XIC, XIO, OTE, OTL, OTU, ONS, OSR, OSF, OSRI, OSFI) 87Execution:ConditionprescanRelay Ladder ActionThe storage bit is cleared to prevent an invalid trigger during the first scan.The output bit is cleared.The rung-condition-out is set to false.rung-condition-in is falseexamine storage bitstorage bit = 0storage bit remains clearedoutput bit is clearedstorage bit = 1storage bit is clearedoutput bit is setendrung-condition-in is trueThe storage bit is set.The output bit is cleared.postscanThe rung-condition-out is set to true.See rung-condition-in is false above.Example:Each time limit_switch_1 goes from set to cleared, the OSF instructionsets output_bit_2 and the ADD instruction increments sum by 5. Aslong as limit_switch_1 stays cleared, sum stays the same value. Thelimit_switch_1 must go from set to cleared again for sum to beincremented again. You can use output_bit_2 on multiple rungs totrigger other operations.Publication 1756-RM003I-EN-P - January 2007