How to wait 1 second using Structured Text? - timer

Question

I am currently writing a program that, when a variable reaches a certain point, a connected light will flash on and off every second. I know the light is properly hooked up, and I know that the program to alternate between on and off works, because it did it multiple times a second. I tried adding a wait timer to slow the flashing down.
Here is the chunk of code I am trying to add:
VAR
delay : TON;
Count : INT := 0;
END_VAR
delay(IN := TRUE, PT:= T#5S);
IF NOT (delay.Q) THEN
RETURN;
END_IF;
delay(IN := FALSE);
When I add it to my code, I get the error invalid time constant.
I'm not sure if it matters too much, but I am using Schneider Electric's EcoStruxure Machine Expert to write and execute my code.
For those that wish to see the entire program, if it would help, here it is:
IF (change < 70) THEN
Light13 := FALSE;
END_IF;
IF (change >= 70) AND (change <= 90) THEN
Light13 := TRUE;
END_IF;
IF (change > 90) THEN
WHILE change > 90 DO
IF (index MOD 2 = 0) THEN
Light13 := TRUE;
END_IF;
IF (index MOD 2 <> 0) THEN
Light13 := FALSE;
END_IF;
delay(IN := TRUE, PT:= T#5s);
IF NOT (delay.Q) THEN
RETURN;
END_IF;
delay(IN := FALSE);
index := index + 1;
END_WHILE;
END_IF;
To avoid getting a repeat question to this question, Timers in PLC - Structured Text, I will again reiterate that I am getting an error using this method. Just wanted to clarify beforehand.
I am not at all set on using this way if there is a better option. Thanks for the help!

Answer 1

Schneider Electric's EcoStruxure Machine Expert is CoDeSys based. So you have a few options.
Use BLINK in Util library
Open library manager, search for BLINK and double click it. Now you have blink block available. Use it like this.
VAR
fbBlink: BLINK;
END_VAR
fbBlink(ENABLE := TRUE, TIMELOW := T#1s, TIMEHIGH := T#300ms, OUT => bSignal);
The advantage of this method that you can set a different times for LOW and HIGH states of your lite and use different signals. For instance, short blink once a 2 seconds error 1 and short blink every half second error 2.
Create your own BLINK function as it is suggested by #Filippo.

Answer 2

If you want to flash your light on and off each second you can use this code:
Declaration part:
FUNCTION_BLOCK FB_Flash
VAR_INPUT
tFlashTime : TIME;
END_VAR
VAR_OUTPUT
bSignal : BOOL;
END_VAR
VAR
fbTonDelay : TON;
END_VAR
Implementation part:
fbTonDelay(IN := NOT fbTonDelay.q, PT:= tFlashTime);
IF fbTonDelay.Q
THEN
bSignal := NOT bSignal;
END_IF
You can call it like this:
fbFlash(tFlashTime := T#1S, bSignal => bFlashLight);
Where bFlashLight is your hardware output.
Now if you want the light to flash when a special condition is fullfilled, you can do like this:
IF bSpecialCondition
THEN
fbFlash(tFlashTime := T#1S, bSignal => bFlashLight);
ELSE
bFlashLight := FALSE;
END_IF
Try to reach your goals with maximum simplicity and clarity.