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4-20 Micro PLC Programmer’s Guide – April 1994
GFK-0804B
Up Counter
The Up Counter turns on an output when the count reaches a specified value (from 0 to
65535 if a register is used to load the counter, or 0 to 32676 if a constant is used). The
output remains on only as long as the count is equal to the specified value. If the count
increases past the specified value, the output goes back to 0.
To program a counter function, enter two inputs (in the example below, I1, and I2), and
two parameters (R1 and 5 in the example).
The first input increments the count value. In this example, each time the Positive
Transition contact transitions on, the count total stored in R1 goes up by 1. The second
input to the counter resets the count total (here, in R1) to 0. It also deactivates the output
coil.
The first parameter of the Up Counter is a register containing a value that is being
incremented (usually, by an input in the application program). Register R1, used in this
example, is not a “retentive” register; it is cleared if power goes off. If the current count
value should be saved with the power off, use a register from R385 to R500.
The second parameter is the counter total. If this number should always be the same,
you can enter it directly, as shown in the example. Or, if you want to be able to change
the counter total, instead enter a register from R385 to R500 as the second parameter for
the timer (see the example Down Counter).
Programming Software Instructions
If you are using the programming software, refer to the instructions on page 4-19.
Example and HHP Instructions
Ladder Diagram Hand-held Programmer
Timing Diagram
Each time input I1 transitions on, the
content of register R1 is incremented.
When it reaches 5, output coil C1
activates.
Input I2 is used to reset counter R1 to
0. It also deactivates coil C1.
I1 C1
START
START
CNTR
OUT
F1
F1
I1
I2
R1
5
C1
Input I1
Register R1
Coil C1
I2
R1
UPCTR
5
Input I2
"
1
0
1
2
3
4
5
0
46128