# Need help on how to program blinking light bulb in PLC

#### black_wing_diaz

##### New Member
Hi,

Does anyone know how to program the below PLC ladder diagram to make the light blub blink? (eg. on & off for 1 secs) Thanks.

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#### instruite

##### New Member
You cant make the Bulb just blink by using relay
You have to use the timer of the PLC, then use the contact of timers to switch the Bulb load

#### black_wing_diaz

##### New Member
instruite said:
You cant make the Bulb just blink by using relay
You have to use the timer of the PLC, then use the contact of timers to switch the Bulb load
Thanks....but how to draw it in the ladder diagram?

#### black_wing_diaz

##### New Member
instruite said:
http://www.plcs.net/chapters/time16.htm
I still don't understand.....Can u drawn an example? Thanks

#### instruite

##### New Member
Are you not able to understand how the timer works???
Drawing ecample is there in the site itslef
http://www.plcs.net/chapters/time16.htm
check out the second figure they have shown an example
Where 0001 is an input contact (it can be any digital input or any contact of other relay which enrgizes the timer T000 (same as u energize the relay)
In second rung there is T000 contact becomes close after the delay of 100 units (can be seconds) from the time the timer was energized which in turns energizes output O500
Hence you get On delay time
See this animation
http://www.plcs.net/chapters/timeran.htm

#### panic mode

##### Well-Known Member
note that plcs come with variety of system bits. some of them are clocks
that can be used just like you did in a original post. those clock bits have
fixed timing (like 0.1sec, 0.2sec, 0.5sec, 1 sec, etc.). to make custom clock you will need timers. now what is the duty cycle of the clock you want? 50%?

you could try somethign like this using single timer:

Code:
    Timer                     Timer
-----|/|-----------------------( )

Timer  Output           Output
-----| |----|/|-----+---------( )
|
Timer  Output    |
-----|/|----| |-----+
Code above will work on any plc, attached examples are for AB and Mitsubishi. note that AB example generates 0.5Hz clock.
you can change this by entering different value in preset. you can change base as well. i rarely have need for 1 sec. base so i decided to use it in this example

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#### panic mode

##### Well-Known Member
you could also do "twisted" chasing lights :-D

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#### black_wing_diaz

##### New Member
Hey....thanks panic, u did it again. Also, thanks instruite for providing the useful website.

#### pacunnin

##### New Member
Hi, i am also looking to turn on a light bulb once i activate an enable input the buld will light for 2 secs then go off for 2 secs then turn back on and repeat the cycle as long as the enable input is active. any ideas?