User Manual

LOGO! functions
4.4 Special functions list - SF
LOGO!
Manual, 06/2014, A5E33039675
173
4.4.15
Up/down counter
Short description
An input pulse increments or decrements an internal value, depending on the parameter
setting. The output is set or reset when a configured threshold is reached. The direction of
count can be changed with a signal at input Dir.
Symbol in LOGO!
Wiring
Description
Input R A signal at input R resets the internal count value to
zero.
Input Cnt The function counts the 0 to 1 transitions at input Cnt.
1 to 0 transitions are not counted.
You can use the following as the input:
• inputs I3, I4, I5, and I6 for fast counting (only
LOGO! 12/24RCE/RCEo and LOGO!
24CE/24CEo): max. 5 kHz, if the fast input is
directly connected to the up/down counter
function block
• any other input or circuit component for counting
low frequency signals (typically 4 Hz)
Input Dir You set the direction of count at input Dir:
Dir = 0: Count up
Dir = 1: Count down
Parameter On: on threshold
Range of values:
0...999999
Off: off threshold
Range of values:
0...999999
StartVal: initial value from which to begin counting
either down or up.
Retentivity for internal counter value Cnt:
/ = No retentivity
R = The status is retentive.
Output Q Q is set or reset, depending on the current value at
Cnt and the set thresholds.
Parameters On and Off
The actual value of another already-programmed function can provide the on threshold On
and the off threshold Off. You can use the actual values of the following functions:
● Analog comparator (Page 188) (actual value Ax – Ay)
● Analog threshold trigger (Page 183) (actual value Ax)
● Analog amplifier (Page 195) (actual value Ax)
● Analog multiplexer (Page 213) (actual value AQ)