Blinking Lamp / Flashing Light - Structured Text

GimmeTheLoot420 · Feb 18, 2016

Hey,

New to the forum so apologise if I break any rules.
I am trying to write a program insturctured text that will allow me to flash a warning lamp on and off indefinitely until it is manually reset, the lamp is triggered by an alarm signal.

I have tried with what I can so far ut keep getting stuck and cant seem to loop the program back on itself, I can get the lamp to switch on then switch off but not to come back on!

I have seen a few examples on this site of how to do it in ladder logic but I would like to implement it using ST. My attempt so far is below, please any criticsm or help is welcomed! Thank you

PROGRAM _CYCLIC Warning_Lamp;
TON_Warning(IN := Alarm_Active_Flag_1 , PT := T#2s );
IF(TON_Warning.Q = TRUE)THEN
Warning_Lamp := TRUE;
END_IF
TON_Warning_2(IN := TON_Warning.Q , PT := T#2s );
IF(TON_Warning_2.Q = TRUE)THEN
Warning_Lamp := FALSE;
END_IF END_PROGRAM

tragically1969 · Feb 18, 2016

GimmeTheLoot420 said:
Hey,

New to the forum so apologise if I break any rules.
I am trying to write a program insturctured text that will allow me to flash a warning lamp on and off indefinitely until it is manually reset, the lamp is triggered by an alarm signal.

I have tried with what I can so far ut keep getting stuck and cant seem to loop the program back on itself, I can get the lamp to switch on then switch off but not to come back on!

I have seen a few examples on this site of how to do it in ladder logic but I would like to implement it using ST. My attempt so far is below, please any criticsm or help is welcomed! Thank you

PROGRAM _CYCLIC Warning_Lamp;
TON_Warning(IN := Alarm_Active_Flag_1 , PT := T#2s );
IF(TON_Warning.Q = TRUE)THEN
Warning_Lamp := TRUE;
END_IF
TON_Warning_2(IN := TON_Warning.Q , PT := T#2s );
IF(TON_Warning_2.Q = TRUE)THEN
Warning_Lamp := FALSE;
END_IF END_PROGRAM

Homework ? A similar question has been asked......

http://www.plctalk.net/qanda/showthread.php?t=101052

GimmeTheLoot420 · Feb 18, 2016

No, this isn't homework! it is a small project at work. Although that question is similar, it is different and not what I want. Thanks anyway though

tragically1969 · Feb 18, 2016

GimmeTheLoot420 said:
No, this isn't homework! it is a small project at work. Although that question is similar, it is different and not what I want. Thanks anyway though

Its not that different, he wants it to flash 50 times a minute until reset, you want it to flash indefinitely until its reset....

The core code is pretty much exactly the same, have you tested the code in the PLC ?

Its generally useful to tell people what PLC you are using, you could use an internal clock for the pulse, most have a few with different timebases available.

jrwb4gbm · Feb 18, 2016

I don't know structured text programming but all flashers work like this. The first timer times the on period. When the time on period is done it is held on and it turns off the output. it also turns on a second timer to time the off period. When the second timer is finished the second timer resets the first timer and then the first timer turns off. By doing that it resets the second timer. The cycle then repeats.

L D[AR2P#0.0] · Feb 18, 2016

Example implementation:

mk42 · Feb 18, 2016

Think about how a TON works, and the first input signal. When it detects the input turning on, it starts counting. It needs that transition from OFF to ON to trigger the timer starting. The way your logic is right now, your TON_Warning_1 starts timing, finishes timing, and then never resets, because the Alarm_Active flag never changes.

What could you do to make the 1st timer reset after the 2nd timer ends?

bkottaras · Feb 18, 2016

Flasher Timer Setup, Free Running,
Replace "Buzzer" with Lamp

-------------------------------------
VAR
Flasher_1 :ton;
Flasher_2 :ton;
END_VAR
-------------------------------------

//------------------------------------------------------------------

Flasher_1(IN:=NOT Flasher_2.q, pt:=T#2s);
Flasher_1_Pulse := Flasher_1.q;

Flasher_2(IN:=Flasher_1.q, pt := T#2s);

IF Flasher_1_pulse
AND Alarm_Active_Bit
AND NOT(Mute_Bit)
THEN
Buzzer := TRUE;
ELSE
Buzzer := FALSE;
END_IF;

tragically1969 · Feb 19, 2016

jrwb4gbm said:
all flashers work like this.

Wow, sweeping statement of the year !! I can assure you that not ALL flashers work like that.....

For a start you could use a flashing beacon and turn the thing on and off.

Blinking Lamp / Flashing Light - Structured Text

GimmeTheLoot420

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tragically1969

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jrwb4gbm

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L D[AR2P#0.0]

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mk42

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bkottaras

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