Installation manual

Publication 1747-RM001G-EN-P - November 2008
Processor Files 1-7
Entering Parameters
There are several parameters associated with Counter instructions. The
following parameters detail the operations of the counter.
Accumulator Value (ACC)
This is the number of false-to-true transitions that have occurred since the
counter was last reset.
Preset Value (PRE)
Specifies the value which the counter must reach before the controller sets the
done bit (DN). When the accumulator value becomes equal to or greater than
the preset value, the done status bit is set. You can use the done bit (DN) to
control an output device.
Preset and accumulated values for counters range from -32,768 to +32,767,
and are stored as signed integers. Negative values are stored in two’s
complement form.
Addressing Structure
Assign counter addresses using the format Cf:e.s/b.
Table 1.9 Counter File Addressing Format
Explanation
C Counter
f File number. For SLC 500 processors the default is 5. A file
number between 9 to 255 can be used for additional storage.
: Element delimiter
e Element number These are 3-word elements.
The range is 0 to 255.
. Word Delimiter
s Word Element 0 to 2
/ Bit delimiter
b Bit Number 0 to 15
Examples
C5:0/15 or C5:0/CU Count up enable bit
C5:0/14 or C5:0/CD Count down enable bit
C5:0/13 or C5:0/DN Done bit
C5:0/12 or C5:0/OV Overflow bit