Allen-Bradley Logix5000 Reference Manual page 128

Chapter 3 Timer and Counter Instructions (TON, TOF, RTO, TONR, TOFR, RTOR, CTU, CTD, CTUD, RES)
128
Example:
When limit_switch_1 is set, light_1 is on for 180 ms (timer_2 is timing). When
timer_3.acc reaches 180, light_1 goes off and light_2 goes on. Light_2 remains
until timer_3 is reset. If limit_switch_2 is cleared while timer_3 is timing, light_1
remains on. When limit_switch_2 is set, the RES instruction resets timer_3
(clears status bits and .ACC value).
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011