Rockwell Automation Publication 1756-RM003N-EN-P - October 2011 131
Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES) Chapter 3
Arithmetic Status Flags: Not affected
Fault Conditions: None
Execution:
Condition Function Block Action Structured Text Action
Prescan No action taken. No action taken.
Instruction first scan EN, TT and DN are cleared.
ACC value is set to 0.
EN, TT and DN are cleared.
ACC value is set to 0.
Instruction first run EN, TT and DN are cleared.
ACC value is set to 0.
EN, TT and DN are cleared.
ACC value is set to 0.
EnableIn is cleared EnableOut is cleared, the instruction does nothing, and the
outputs are not updated.
N/A
EnableIn is set When EnableIn transitions from cleared to set, the
instruction initializes as described for instruction first
scan.
The instruction executes.
EnableOut is set.
EnableIn is always set.
The instruction executes.
Reset When the Reset input parameter is set, the instruction
clears EN, TT and DN and sets
ACC = zero.
When the Reset input parameter is set, the instruction
clears EN, TT and DN and sets
ACC = zero.
Postscan No action taken. No action taken.