Nematron Pointe Controller - Manual (Page 359)

Pointe Controller User Guide Appendix C: Ladder Diagram Block Reference
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Once the block is inserted, you can double-click on it to configure it.
Functional Description
This block always passes the Enable input state (EN) through to the Enable Out
output state (ENO) without change; when EN becomes on, ENO is turned on, and
when EN becomes off, ENO is turned off.
When EN becomes on, the block function is executed and the following
conditions are evaluated in order:
1. The Reset and Preset inputs (R and L) are checked and the Counter Value
output (CV) is changed accordingly:
If R is true and L is false, then CV is set to 0 and the function skips to
#3 below.
If R is false and L is true, then CV is set to the Preset Value input (PV)
and the function skips to #3 below.
If R and L are both true, then R takes precedence (see above).
If R and L are both false, then CV is not changed and the function
proceeds to #2 below.
2. The Count Up and Count Down inputs (CU and CD) are checked and CV is
changed accordingly:
If CU is true, CD is false, and CV is less than PV, then CV is
incremented by 1 and the function proceeds to #3 below.
If CU is false, CD is true, and CV is greater than 0, then CV is
decremented by 1 and the function proceeds to #3 below.
In all other conditions, CV is not changed.
3. The Output Up and Output Down bits (QU and QD) are set according to
the current value of CV:
If CV is greater than or equal to PV, then QU is set to true and QD is
set to false.
If CV is less than or equal to 0, then QU is set to false and QD is set to
true.
If CV is between 0 and PV, then both QU and QD are set to false.
The block function is executed every time the ladder is scanned , so long as EN
remains on.
NOTE: Because the frequency of the count is based on the project’s Scan Interval ,
it should not be used to gauge real time. To gauge real time, use a Timer .