Allen-Bradley Logix5000 Reference Manual page 142

Chapter 3 Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES)
Arithmetic Status Flags:
Fault Conditions:
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The accumulated value continues incrementing, even after the .DN bit is set. To
clear the accumulated value, use a RES instruction that references the counter
structure or write 0 to the accumulated value.
Not affected
None
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011