You use the Positive Edge Trigger function block to trigger events based on the rising transition of a logical signal. For example, you can use the block to trigger a machine startup when a valve opens.
The output of this block should not be used in a different module unless you are certain that the scan rates match and will not be changed in the future.
You can lengthen the pulse by using an Off-delay Timer function block, or you can use the pulse output to set a latch.