32.5.1.2 Explanation of the Positive Transition (PT)
Instruction
-
When a PT instruction bit variable turns ON, only
the first scan turns ON. Subsequent scans are OFF even though the
bit variable may be in the ON state. You can use the PT instruction
for counting the number of ON states.
-
You cannot use a NO instruction without including
another instruction just to the left of the right power bar. The
other instruction can be an output instruction or any instruction
other than an input.
Program Example
The variable (Start) turns ON, and then the
variable motor turns ON.
After a scan is executed once, the variable
motor will be turned OFF.
The variable (Motor) remains OFF because the
upward transition of the variable (Start) is not detected.
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