help Pulse instruction in AllenB

MrQ · May 30, 2013

Hello,

I am starting to think I am stupid. New to compactlogix and rslogix.

I just need to generate a 2 seccond pulse.

INPUT goes true output shall be true for 2 secconds and then turn false even if input is true.

I have been trying TOF, TON etc but i just can't get it to work.

HELP!

Anirban Hazra · May 30, 2013

You can achieve this in many ways.One such way is this:



|Input   O1          +------+

|-| |--[ONS]---------| TOF  |

|                    |  T1  |

|                    +------+

|

|T1.DN                 Output 

|-| |-------------------( )

m-hamizan · May 30, 2013

|T2.DN...............+------+
|-|/|-------------| TON |

|.......................|.. T1.. |

|.......................+------+

|T1.DN................+------+
|-||--------------| TON |

|.......................|.. T2.. |

|........................+------+

|T1.DN................Output1
|-|/|-------------------( )

OUTPUT1=2 SECOND PULSE

kekrahulik · May 30, 2013

It may help your thinking to use the Timer.TT bit instead of the timer done bit. This is true while the timer is timing.

This will give a 2 sec pulse is the input remains true for 2 or more seconds:

---|input|-------------(Timer)---

---|Timer.TT|---------(Output)---

If you want the 2 second pulse to happen even if the input goes false, then you need to "seal in" the input with the timer.TT bit:

------|input|-------------(Timer)---
| |
| --|Timer.TT|--|

---|Timer.TT|------------(Output)---

Lancie1 · May 30, 2013

INPUT goes true output shall be true for 2 secconds and then turn false even if input is true.

What do you want to happen when the input goes from true to false, then back to true? Should you get another 2-second pulse, or not? In other words, do you want the pulse to repeat, or just strictly ON for the first time that the input goes true? Or do you want the pulse to go on 2 seconds, off 2 seconds, then repeat, as long as the input is true?

TConnolly · May 30, 2013

Define tag PulseTimer of type timer.
Define Alias tag Pulse2Sec, base tag is PulseTimer.TT



      Trigger

-+------] [------+----------+-TON--------------+-(EN)

 |               |          |Timer  PulseTimer |-(DN)

 |               |          |PRE          2000 |

 | PulseTimer.TT |          |ACC             0 |  

 +------] [------+          +------------------+

This timer will begin timing whenever trigger is true. Should trigger last less than two seconds or more than two seconds, the TT bit will still be true for only two seconds.

Elsewhere in your program, wherever you need the pulse, use the Pulse2Sec alias tag - it will improve program clarity.



  Pulse2Sec                        Output

-----] [----------------------------( )---

m-hamizan · May 30, 2013

http://i302.photobucket.com/albums/nn82/campedak/1secondpulse.jpg
attachment

help Pulse instruction in AllenB

MrQ

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Anirban Hazra

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m-hamizan

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kekrahulik

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Lancie1

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TConnolly

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m-hamizan

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