108 Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Chapter 2 Bit Instructions (XIC, XIO, OTE, OTL, OTU, ONS, OSR, OSF, OSRI, OSFI)
Execution:
Example: Each time limit_switch_1 goes from set to cleared, the OSF instruction sets
output_bit_2 and the ADD instruction increments sum by 5. As long as
limit_switch_1 stays cleared, sum stays the same value. The limit_switch_1 must
go from set to cleared again for sum to be incremented again. You can use
output_bit_2 on multiple rungs to trigger other operations.
Condition Relay Ladder Action
Prescan. The 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 true. The storage bit is set.
The output bit is cleared.
The rung-condition-out is set to true.
Postscan. See rung-condition-in is false above.
Rung-condition-in is false.
End
Examine
storage bit.
Storage Bit = 0
Storage Bit = 1
Storage bit remains
cleared.
Output bit is cleared.
Rung-condition-out is
set. to false.
Storage bit is cleared.
Output bit is set.
Rung-condition-out is
set to false.
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