Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 71)

Timers and Counters
Chapter 8
8Ć4
Retentive Timer On/Reset
Retentive Timer On
Purpose: The Retentive Timer On accumulates the amount of time that the
preconditions of its rung are true. It controls one or more outputs (by means of
other rungs) after the total accumulated time is equal to the preset time.
Whenever the rung is false, the accumulated time is retained. If the outputs
have been energized, they remain on. The accumulated time and energized
outputs are retained if power is removed from the processor. A separate rung,
containing a retentive timer reset instruction must be programmed in order to
reset the accumulated time to zero and turn off the outputs.
010
00
RTO
030
1.0
PR 150
AC 000
When the rung condition becomes:
True
Timer begins counting time-base intervals.
Bit 15 is set when AC=PR and the timer stops timing.
Bit 17 is set.
False
Accumulated value is retained.
Bit 15 - no action is taken.
Bit 17 is reset.
Important: The RTO instruction retains its AC value when the:
Rung condition turns false.
Processor changes to remote/program mode.
Power outage occurs and memory backup is maintained.
Retentive Timer Reset
Purpose: The Retentive Timer Reset instruction resets the accumulated value
and timed bit of the retentive timer to zero. This instruction is given the same
word address as its corresponding RTO instruction. When the rung conditions
go true, the RTR instruction resets the ac value and resets the status bits to zero.
010
00
RTR
030
PR 150
AC 000