User Manual

LOGO! functions
4.4 Special functions list - SF
LOGO!
Manual, 06/2014, A5E33039675
153
● Wiping relay(pulse output) (Page 146) (current time Ta)
● Edge triggered wiping relay (Page 148) (current time Ta)
● Asynchronous pulse generator (Page 150) (current time Ta)
● Stairway light switch (Page 154) (current time Ta)
● Multiple function switch (Page 156) (current time Ta)
● Stopwatch (Page 171) (actual value AQ)
● Threshold trigger (Page 180) (actual value Fre)
Select the required function by the block number. The timebase is configurable. For
information on valid ranges and parameter defaults, refer to the On-delay (Page 136) topic.
Timing diagram
Functional description
The 0 to 1 transition at input En triggers a random on-delay time between 0 s and T
H
. The
output is set when the on-delay time expires and if the signal at input En remains hi at least
for the duration of this time.
The time is reset if input En is reset before the on-delay time has expired.
A 1 to 0 transition at input EN triggers a random off-delay time between 0 s and T
L
.
LOGO! resets the output after the off-delay time expires, provided input En remains lo at
least for the duration of this time.
LOGO! resets the time if the signal at input En changes to 1 again before the off-delay time
expires.
If the block is retentive, LOGO! resets output Q and the expired time to the values before a
power failure; if the block is not retentive, LOGO! resets output Q and the expired time to
defaults after a power failure.