Automating Manufacturing Systems - Process Control and ...

plc timers - 9.10
A
TOF
Timer T4:0
Time Base 0.01
Preset 350
Accum. 0
(DN)
(EN)
A
T4:0 EN
T4:0/DN
T4:0/TT
T4:0.Accum.
0
3
3.5
0 3 6 9.5 10 16 18 20
Figure 9.10
An Allen Bradley Off-Delay Timer
Retentive off-delay (RTF) timers have few applications and are rarely used, therefore
many PLC vendors do not include them.
An example program is shown in Figure 9.11. In total there are four timers used in
this example, T4:1 to T4:4. The timer instructions are shown with a shorthand notation
with the timebase and preset values combined as the delay. All four different types of
counters have the input I/1. Output O/1 will turn on when the TON counter T4:1 is done.
All four of the timers can be reset with input I/2.