Eaton easyE4 Manual page 304

6. Function blocks
6.1 Manufacturer function blocks
300
The mark-to-space ratio is 1:1.
The signals of channels A and B must be offset by 90°. Otherwise the count direction
cannot be determined.
Positive count direction
If the rising edge at channel A is detected before the rising edge at channel B, the
counter will count up. This means that the counter will be incremented by 1 after there
is a rising edge at channel A followed by a rising edge at channel B. The same applies to
the falling edges in sequence at channel A and channel B. The counter relay's result will
be incremented and output at output QV.
Figure 160: CI function block counting up; QV=QV+4
Negative count direction
If the rising edge at channel B is detected before the rising edge at channel A, the
counter will count up. This means that the counter will be decremented by 1 after there
is a rising edge at channel A followed by a rising edge at channel B. The counter relay's
result will be decremented and output at output QV.
Figure 161: CI function block counting down; QV=QV-4
NOTICE
Avoid unforeseeable switching states.
Switch C, CF, CH, CI function blocks only at one single point in the pro-
gram.
Otherwise, previous counts will be overwritten.
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