User Manual

LOGO! functions
4.3 Special functions
LOGO!
Manual, 06/2014, A5E33039675
127
4.3
Special functions
Because of their different input designation, you can see right away that there is a difference
between the special functions and basic functions. Special functions (SFs) contain timer
functions, retentive functions and various parameter assignment options, which allow you to
adapt the circuit program to suit your own requirements.
This section provides you with a brief overview of input designations and with some
particular background information on SFs (Page 131).
4.3.1
Designation of the inputs
Logical inputs
The following connectors enable you to create a logical link to other blocks or to the inputs of
the LOGO! unit:
●
S (Set):
A signal at input S sets the output to logical "1".
●
R (Reset):
The reset input R takes priority over all other inputs and resets the outputs.
●
Trg (Trigger):
This input triggers the start of a function.
●
Cnt (Count):
This input counts pulses.
●
Fre (Frequency):
LOGO! applies frequency signals to be evaluated to this input.
●
Dir (Direction):
This input determines the direction, + or -.
●
En (Enable):
This input enables a block function. When this input is "0", the block ignores all other
signals.
●
Inv (Invert):
A signal at this input inverts the output signal of the block.
●
Ral (Reset all):
A signal at this input resets all internal values.
●
Lap
(for the stopwatch function)
A signal at this input pauses the stopwatch.
Note
Unused logical inputs of special functions default to logical "0".