Hi how do i get a countdown timer to count from a certain value to zero when i press the start button, using function blocks?
The way I would do it is: (a) Use a timer function block (e.g. TON) to generate a rising edge on a BOOL variable at the frequency you want the counter to decrement. There are various ways to do this, and many examples on the internet. (b) Use the count down (CTD) function block to count down from the preset value when the start button is pressed, using the timer as the CD input. You could also use a SEL block to decrement a counter value based on a fixed-frequency pulse. Hope this helps.
