Beckhoff TwinCAT FAQ - How to declare a timer and use the timer TON module TC3

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 TON function block function:When the input is high, the timer starts timing. CV represents the current

value of the timer, while PV is the target value of the timer. When the value of CV equals the value of

PV, the outputis set to 1.

Press F2 at the next place in the main program and add the TON function block.







I named it t1 here

Here, t1_timer and t1_output are bool values, while t1_current is a time value.

Click login and start

Check the running status of the program, as shown in the figure below:The above figure shows

the current situation of t1. We change the value of t1_timer to true, and the result is


It can be seen that when t1_cunrrent=3s, Q is set to 1.

F-TRIG function blockFunction block

function: When the input generates a falling edge, the output will remain at 1 for the next cycle.

Press F2 where the main program continues and add the F-TRIG function block.




















I name it TRIG1



Here, trig1_clk and trig1_output are both bool values.Due to the special function of the trigger,

a breakpoint is set at the end of the program to view the program execution result. After the

login procedure, there is a return statement at the end of the program. A breakpoint is set

here, as shown in the figure:
































Due to the special function of the trigger, a breakpoint is set at the end of the program to view the

program execution result. After the login procedure, there is a return statement at the end of

the program. A breakpoint is set here, as shown in the figure:



Due to the special function of the trigger, a breakpoint is set at the end of the program to observe the

program execution result. After the login procedure, there is a return statement at the end of the

program. A breakpoint is set here, as shown in the figure:


The word becomes red to indicate that the line where RETURN is currently located is the breakpoint ofthe program. When the program runs, it will stop running when it encounters the breakpoint. After the

program runs, this line will turn yellow and an arrow will appear at the line number in front of it,

indicating that the program is currently staying on this line.








Observe the program running status. At this time, if trig1_clk is true, press the keyboard F11 or find

step into in the PLC to achieve single-step execution.























Keep STEP INTO until the following figure appears: At this time, trig1_clk is exactly at the

falling edge, and according to the F-trig function, trig1_output will become true next, as shown in

the figure









After one PLC cycle, it returns to false, so the function block test is complete.