Is there a timer function or variable in Codesys as in arduino millis()?

Question

Is there a timer function or variable in Codesys as in arduino millis() ?

If not, how can I create a timer?

Thanks!

Answer 1

In CoDeSys function TIME() return time in milliseconds from PLC start. If you want to start the count on the event you can use triggers to create a time point.

VAR
   tStarted, tElapsed : TIME;
END_VAR

fbR_TRIG(CLK := xStart);
IF (fbR_TRIG.Q) THEN
    tStarted := TIME();
END_IF;

tElapsed := TIME() - tStarted;

And rest follows like reset the timer, pause counting, etc.

Answer 2

You can build one yourself. Here an example:

Declaration part:

FUNCTION_BLOCK FB_Millis
VAR_INPUT
    timer : TON := (IN:=TRUE,PT:=maxTime);
END_VAR
VAR_OUTPUT
    tElapsedTime : TIME;
END_VAR
VAR
    maxTime : TIME := UDINT_TO_TIME(4294967295);
    //timer : TON := (IN:=TRUE,PT:=maxTime);
END_VAR

Implementation part:

timer();
tElapsedTime := timer.ET;

You call it cyclically like this:

fbMillis();

And retrieve the result like this:

tElapasedTime := fbMillis.tElapsedTime;

FB_Millis overflows after 49days 17hours 2minutes 47seconds and 295ms.

If you want to compare the elapsed time from fbMillis.tElapsedTime with another variable you do like this:

IF fbMillis.tElapsedTime < tAnotherTimeVar 
THEN
 ; //Do something
ELSE
 ; //Do something else
END_IF

If you instead just want a simple timer you need the TON Function Block:

Declaration part:

//2 seconds timer
mySimpleTimer : TON := (PT:=T#2s);

Implementation part:

mySimpleTimer();

// your code here

//Start timer
mySimpleTimer.IN := TRUE;

//Check if timer has reached desired time
IF mySimpleTime.Q
THEN
 //Do something here
 mySimpleTimer.IN := FALSE;
END_IF