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Chapter 4. Ladder Diagram (LD) Programming
Each counter uses a one-dimensional, three-word array of %R, %W, %P, %L, or symbolic memory to
store the following information:
Current value
Word 1
(CV)
Preset value
Word 2 When the Preset Value (PV) operand is a variable, it is normally set to a
(PV)
Control word
Word 3
Word 3: Control Word Structure
15
14
13
12
11
10
Note: Bits 0 through 13 are not used for counters.
134
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
The first word (CV) can be read but should not be written
to, or the function may not work properly.
different location than word 2 in the timer's or counter's three-word
array.
If you use a different address and you change word 2 directly, your
■
change will have no effect, as PV will overwrite word 2.
If you use the same address for the PV operand and word 2, you can
■
change the Preset Value in word 2 while the timer or counter is
running and the change will be effective.
The control word stores the state of the Boolean inputs and outputs of
its associated timer or counter, as shown in the following diagram:
The third word (Control) can be read but should not be
written to; otherwise, the function will not work.
9
8
7
Reserved
Reset input
Enable input, previous execution
Q (counter/timer status output)
EN (enable input
Warning
Warning
6
5
4
3
2
1
0
GFK-2950C
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