Plc

SarahPLC · Nov 20, 2005

Working on a plc project if you have a timer as a trigger, activated with a switch, is there any way to change the time for the timer if manually a second input is activated?

do I have to disable input 1 for timer to trigger with a different configuration when input 2 is set?

darrenj · Nov 20, 2005

I think i understand what you are saying..

Input 1 if selected gives you a time of say 30 seconds..
input 2 if selected gives you a time of say 2 mins..
Is that right..
If so then No you dont have to disable input 1 (But it would be easier) and it would also be easier to use two timers..

What kind of PLC?

TConnolly · Nov 20, 2005

What PLC are you using?

If I understand your question correctly this is what you want.

If Not Input 2 then move VALUE1 into the timer preset
IF Input 2 then move VALUE2 into the timer preset
If Input 1 then run the timer.

In this ladder example for an AB PLC, if input 2 is on, the timer will run for 10 seconds. If input 2 is off, the timer will run for 20 seconds.



  INPUT2

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

                  |10      |

                  |T4:0.PRE|

                  +--------+

  INPUT2

 --]/[------------+MOV-----+---

                  |20      |

                   |T4:0.PRE|

                   +--------+

  INPUT1

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

                   |T4:0    |

                  |0       +-( )- DN

                  |0       |

                   +--------+

darrenj · Nov 20, 2005

Much better than my attempt..Listen to Alaric..he will see you straight..

D

darrenj · Nov 20, 2005

Dont mean to nit pick Alaric but what happens if only input 2 is on? The timer will not work...

SarahPLC · Nov 20, 2005

Thanks

im using plc 1760-L20BBB on picosoft

elevmike · Nov 20, 2005

SarahPLC said:
Working on a plc project if you have a timer as a trigger, activated with a switch, is there any way to change the time for the timer if manually a second input is activated?

do I have to disable input 1 for timer to trigger with a different configuration when input 2 is set?

If I get your question right...

You can use a second input to alter the timer value by holding the second input on for the desired time duration. What you would do is have the 1st timer reference a spicific memory location. The second input would activate a second timer, and output that timers current value into the reference memory location while the input is on.

something like so..



   input 1

---||--------------[timer 1]

                   preset = referance 005

 

 

  input 2

----||-------------[timer 2]

                   [load current value of timer 2]

                   [OUT mem. 005]

This way you can change the timer 1 preset value by holding down a button on input 2 for the duration of the desired time.

TConnolly · Nov 20, 2005

Thats going to be a little more difficult then.
I dont believe that the PICO supports programatically changing the timer preset. Maybe it can be done, but I'm not aware of how.

I suggest you use two timers.



      ____

 [I1]-[I2]-{T1 10

 [I1]-[I2]-{T2 20

 [T1]|-----{Q1

 [T2]|

TConnolly · Nov 20, 2005

darrenj said:
Dont mean to nit pick Alaric but what happens if only input 2 is on? The timer will not work...

Darren, I didnt read the post that way. I read it as input one controls the timer, input two controls how long the timer is.

Was my understanding incorrect? It certianly would not be the first time.

darrenj · Nov 20, 2005

Alaric said:
Darren, I didnt read the post that way. I read it as input one controls the timer, input two controls how long the timer is.

Was my understanding incorrect? It certianly would not be the first time.

You may be right..I just assumed there was two times..why else would you use two bits to turn the same timer on? bit 1=30 seconds..bit 2 = 2 mins.... oh well i have some roblems of my own to deal with now..

see my next post !!

rsdoran · Nov 21, 2005

You will need 2 timers. What you can do is use a selector switch will do the same thing Alaric did above. Selector switch is assigned to I2, since it is a 2 position selector switch all we need to use is 1 input. Something along these lines.



  Start 

    I1               SM1

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

|    M1     I3       TT1

|---[ ]-+--[ ]-------( )--

|     |    I3        TT2

|     +----[/]-------( )--

| Stop

|    I2              RM1

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

Use Timer1 or 2 as an OR function where needed. I was too lazy to do more.

This code/ladder **** gets worse every time i do it.

TConnolly · Nov 21, 2005

rsdoran said:
This code/ladder **** gets worse every time i do it.

Frustrating, isn't it?

I edited my post probably five or six times before I got the code/ladder to look like I wanted it to.

Steve Bailey · Nov 21, 2005

rsdoran said:
This code/ladder **** gets worse every time i do it.

Don't click on 'Preview Post' before submitting your code. The preview seems to strip extra spaces so that your text doesn't line up with your ladder elements.

See my two examples in the practice area.

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