User's Manual

LOGO! functions
4.4 Special functions list - SF
LOGO!
258 Manual, 04/2011, A5E03556174-01
Select the required function by the block number. For information on parameter defaults,
refer to the
On-delay (Page 160) topic.
Parameters KC, TI
Please note:
● If parameter KC has value 0, the "P" function (proportional control) will not be executed.
● If parameter TI has value 99:59 m, the "I" function (integral-action control) will not be
executed.
Parameter p (number of decimals)
Applies only to the PV, SP, Min and Max values displayed in a message text.
Timing diagram
The nature, manner and speed with which the AQ changes depend on the parameters KC
and TI. Thus, the course of AQ in the diagram is merely an example. A control action is
continuous; therefore the diagram portrays just an extract.
4
63
39
0D[
0LQ
PV
0T
$4
'LU
5
$0
ൻ
཰
൹
ཱི
1. A disturbance causes the PV to drop, as Dir is positioned upwards, AQ increases until PV
corresponds again to SP.
2. A disturbance causes the PV to drop, as Dir is positioned downwards, AQ decreases until
PV corresponds again to SP.
It is not possible to change the direction (Dir) at runtime of the function. The change is
shown here for illustrative purposes only.
3. As AQ is set to 0 by means of the input R, PV changes. This is based on the fact that PV
increases, which on account of Dir = upwards causes AQ to drop.