Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 139)

Chapter 8
Using Basic Instructions
8–20
Use the RTO instruction to turn an output on or off after its timer has been on
for a preset time interval. The RTO instruction is a retentive instruction that
lets the timer stop and start without resetting the accumulated value (ACC).
The RTO instruction retains its accumulated value when any of the following
occurs:
•
Rung conditions become false.
•
You change controller operation from the RRUN, RCSN, or RSSN mode
to the RPRG mode.
•
The controller loses power.
•
A fault occurs.
Using Status Bits
This Bit Is Set When
And Remains Set Until One
of the Following
Timer Done Bit DN (bit 13)
accumulated value is equal to
or greater than the preset value the appropriate RES instruction
is enabled
Timer Timing Bit TT (bit 14)
rung conditions are true and
the accumulated value is less
than the preset value
rung conditions go false or
when the done bit is set
Timer Enable Bit EN (bit 15) rung conditions are true rung conditions go false
Important: To reset the retentive timer’s accumulated value and status bits
after the RTO rung goes false, you must program a reset (RES)
instruction with the same address in another rung.
Entering the Instruction
You enter the instruction from within the program monitor functional area.
P 0 0 0 R T O A D D R
T 2
P 0 0 0 R T O P R E
* * * 1 2 0
P 0 0 0 R T O A C C
* * * * * 0
P 0 0 0 R T O B A S E
0 . 0 1 S E C
(EN)
(DN)
RTO
RETENTIVE TIMER ON
Timer
T4:2
Time Base 0.01
Preset 120
Accum 0
Execution Times (
µ
sec) when:
True False
38.34 27.49
Ladder representation:
Retentive Timer (RTO)
2
L FUN ENT
To enter the function code, press: