Allen-Bradley Logix5000 Reference Manual page 139

Arithmetic Status Flags:
Fault Conditions:
Condition
Prescan
Instruction first scan
Instruction first run
EnableIn is cleared
EnableIn is set
Reset
Postscan
Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES)
Not affected
None
Execution:
Function Block Action
No action taken.
EN, TT and DN are cleared.
ACC value is not modified.
EN, TT and DN are cleared.
ACC value is not modified.
EnableOut is cleared, the instruction does nothing, and the
outputs are not updated.
Function Block
When EnableIn transitions from cleared to set, the
instruction initializes as described for instruction first
scan.
The instruction executes.
EnableOut is set.
When the Reset input parameter is set, the instruction
clears EN, TT and DN and sets
ACC = zero.
No action taken.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Structured Text Action
No action taken.
EN, TT and DN are cleared.
ACC value is not modified.
EN, TT and DN are cleared.
ACC value is not modified.
N/A
EnableIn is always set.
The instruction executes.
When the Reset input parameter is set, the instruction
clears EN, TT and DN and sets
ACC = zero.
No action taken.
Chapter 3
139