Issue
Why don't my  Structured Text Timers  reset?

Product Line
EcoStruxure Control Expert

Environment
Control Expert v14.1


Resolution
If you are used to high level languages for a computer, some things in PLCs are not immediately obvious. For some developers timers are one of them. In a timer such as the TON procedure the first parameter is a Boolean that controls the timer. If it is True,  the timer runs. However, the timer is solved and the clock is reset if the parameter is False.  This putting the timer within a conditional will prevent the timer from resetting.
The following code snippet will run to 10 seconds and then continue:


The following will run for 10 seconds and stop:

Released for: Schneider Electric Singapore