Industrielle styresystemer - Wiki
Here are the function blocks for a pulser. There are two of these, one gives out a pulse with a duration of 3 seconds (PulseThreeSeconds) and the other for 4 seconds (PulseFourSeconds). The times in these are hardcoded because they were used a couple of times in the program, and it would have been more work to add a variable to control the pulse length than to make two different ones.
This works so that if it gets a boolean value in, it gives out a pulse that lasts for 3 seconds or 4 seconds respectively. This is regardless if you turn off the input or let it stay on. When the pulse is finished, the function block needs a new rising edge input to send a new pulse.