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Chapter 4. Ladder Diagram (LD) Programming
Word 1: Current value (CV)
Word 2: Preset value (PV)
When the Preset Value (PV) operand is a variable, it is normally set to a 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.
Word 3: Control word
The control word stores the state of the Boolean inputs and outputs of its associated timer or
counter, as shown in the following diagram:
15
14
13
12
Note: Bits 0 through 13 are used for timer accuracy.
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PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
Do not use two consecutive words (registers) as the
starting addresses of two timers. Logic Developer - PLC
does not check or warn you if register blocks overlap.
Timers will not work if you place the current value of a
second timer on top of the preset value for the
previous timer.
The first word (CV) can be read but should not be
written to, or the function may not work properly.
11
10
9
8
Reserved
Reset input
Enable input, previous execution
Q (counter/timer status output)
EN (enable input
The third word (Control) can be read but should not be
written to; otherwise, the function will not work.
Warning
Warning
7
6
5
4
Warning
3
2
1
0
GFK-2950C
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