Siemens LOGO!, Manual

Page: 177 / 534

LOGO! functions
4.4 Special functions list - SF
LOGO!
Manual, 04/2011, A5E03556174-01
177
4.4.8 Random generator
Short description
The output of the random generator is set or reset within a configured time.
Symbol in LOGO! Wiring Description
Input En A positive edge ( 0 to 1 transition) at input En
(Enable) triggers the on-delay time of the random
generator.
A negative edge ( 1 to 0 transition) at input En
(Enable) triggers the off-delay time of the random
generator.
Parameter The on-delay is set at random to a value between 0 s
and T
H
.
The off-delay is set at random to a value between 0 s
and T
L
.
4
(Q
3DU
Output Q Output Q is set when the on-delay has expired and if
En is still set. It is reset when the off-delay has
expired, provided En was not set again meanwhile.
Parameter T
H
and T
L
Note the defaults of the T
H
and T
L
parameters listed in topic Time response (Page 151).
The on-delay time TH and the off-delay time TL can be provided by the actual value of
another already-programmed function. You can use the actual values of the following
functions:
●
Analog comparator (Page 218) (actual value Ax – Ay)
● Analog threshold trigger (Page 213) (actual value Ax)
● Analog amplifier (Page 226) (actual value Ax)
● Analog multiplexer (Page 248) (actual value AQ)
● Analog ramp (Page 251) (actual value AQ)
● Mathematic instruction (Page 265) (actual value AQ)
● PI controller (Page 256) (actual value AQ)
● Up/down counter (Page 201) (actual value Cnt)
If your LOGO! is a LOGO! 0BA7, you can additionally use the actual values of the following
functions:
●
Analog filter (0BA7 only) (Page 271) (actual value AQ)
● Average value (0BA7 only) (Page 276) (actual value AQ)
● Max/Min (0BA7 only) (Page 273) (actual value AQ)
● On-delay (Page 160) (current time Ta)