Siemens S7-200,cpu 212.

[zuhairhaider]

Hi to all,
Yesterday I asked a Question but I didn't get a single reply. Why?I don't know but its very necessary if any one can help me to get out from this problem.
The problem is:
I want to start a operation for 5 Seconds and then the same operation is shut down for 20 seconds and again start the same operation for 5 Seconds. So it will be a pulse of total 30 Seconds which is On for 5 Seconds and Off for 20 Seconds and then again On for 5 Seconds. Well I solved this problem by drawing its Ladder.I am using SIEMENS S7 200, CPU-212.

But if I want to keep the same operation,15 Seconds off, then On for 5 Seconds and then again Off for 10 seconds I am unable to draw its Ladder diagram.The PLC is same.Now the Pulse will be 15 Seconds Off,5 Seconds ON and 10 Seconds Off.

All this process is to be done with ON DELAY TIMER only.
So please suggest how would I do this.

Hope this time I would get some suggestions.

Regards.
Zuhair Haider

 

[tom_stalcup]

Well... I don't know much about Siemens plc's.... And I was out of computer contact yesterday, so I didn't see your initial post. But I can hazard a guess for why no-one answered your thread yesterday. A lot of people here have an aversion to doing people's homework problems for them, and this sounds like a classic homework problem. They'll help you out, and correct you if you are going in the wrong direction, but you'll need to show that you've done some work on your own.


Now, with that said....

Go ahead and show us what you have come up with so far for the first solution. It shouldn't be too horribly hard to modify that one to achieve the results you want for the second problem.

What ideas have you tried so far?

 

[marius]

i've seen the first post... but did not understand what Zuhair wants (besides that it is his homework)...

well.. Zuhair, first time you need to practise boolean algebra ... second time you have to think about that more....

you already know you need three OnDelay Timers...
first is running for 15 sec
then second is running for 5 sec
then third is running 10 sec

simply set output then first timer is finished and second is not, in other cases... output is cleared

 

[Damir]

There best way to solve that is a combination of different timer with sequence control bits (SCR).

The online help for "SCR" has already a sample for such a purpose.

------------------------------

STL
NETWORK 1
// On the first scan enable State 1
LD SM0.1
S S0.1 1
NETWORK 2
// Beginning of State 1 control region
LSCR S0.1
NETWORK 3
// Control the signals for Street 1
LD SM0.0
S Q0.4 1 // Set: Turn on the red light
R Q0.5 2 // Reset: Turn off the yellow and green lights
TON T37 +20 // Start a 2-second timer
NETWORK 4
// After a 2 second delay, transition to State 2
LD T37
SCRT S0.2
NETWORK 5
// End of SCR region for State 1
SCRE
NETWORK 6
// Beginning of State 2 control region
LSCR S0.2
NETWORK 7
// Control the signals for Street 2
LD SM0.0
S Q0.2 1 // Set: Turn on the green light
TON T38 +250 // Start a 25-second timer
NETWORK 8
// After a 25 second delay, transition to State 3
LD T38
SCRT S0.3
NETWORK 9
// End of SCR region for State 2
SCRE

----------------------------------

 

[ivo.maenen]

Try 'grafcet' or Sequential Functional Chart (SFC).

 

[rsdoran]

Hi to all,
Yesterday I asked a Question but I didn't get a single reply. Why?I don't know but its very necessary if any one can help me to get out from this problem.
The problem is:
I want to start a operation for 5 Seconds and then the same operation is shut down for 20 seconds and again start the same operation for 5 Seconds. So it will be a pulse of total 30 Seconds which is On for 5 Seconds and Off for 20 Seconds and then again On for 5 Seconds. Well I solved this problem by drawing its Ladder.I am using SIEMENS S7 200, CPU-212.

But if I want to keep the same operation,15 Seconds off, then On for 5 Seconds and then again Off for 10 seconds I am unable to draw its Ladder diagram.The PLC is same.Now the Pulse will be 15 Seconds Off,5 Seconds ON and 10 Seconds Off.

All this process is to be done with ON DELAY TIMER only.
So please suggest how would I do this.

Hope this time I would get some suggestions.

Regards.
Zuhair Haider

This is the S7-200 system manual: http://cache.automation.siemens.com/dnl/TUyMTY3NwAA_1109582_HB/S7-200_E.pdf

Chapter 6 explains the instruction set. There are numerous compare instructions which would allow you to use one timer for each routine that you create, you just use different conditions to determine which time routine is used. The timer section shows an example of a compare instruction being used.

I do not have Micro/Win so could not offer an example.

 

[rsdoran]

But if I want to keep the same operation,15 Seconds off, then On for 5 Seconds and then again Off for 10 seconds I am unable to draw its Ladder diagram.The PLC is same.Now the Pulse will be 15 Seconds Off,5 Seconds ON and 10 Seconds Off.

In this case you would use a rung to start the timer and set the preset time to 30 seconds and automatically reset when it gets to 30 seconds. You would just use the compare instruction(s)
for the time period of 16 through 20 seconds to activate your bit.

 

[Terry Woods]

"Using On-Delay Timers only..."

I've never been one for using explicit OFF-Delay Timers. I've always used ON-Delay Timers to perform the Off-Delay effect.

In general, the concept is as follows...

Turn ON

 Output      +-------+

---|/|-------+ TIMER +-------(   ) Turn OFF

             +-------+              Output





Turn ON   Turn OFF

 Output    Output

---| |---+---|/|---(   ) Output

         |

 Output  |

---| |---+

.
Now it should simply be a matter of getting all of your ducks in a row.

You need to consider how YOU would control the required action if YOU were the controller!

 

[zuhairhaider]

Dear Marius,
thx for ur reply.Its not my Homework.actually I m in this field only and while i m discussing with my friend i found some problem in the second problem, thats y i post the question here.
well i know that its required 3 timers but still i m unable to draw its ladder.
I m facing the problem in 1st stage where i have to shut Off the operation for 15 seconds. I m unable to proced further.

plz suggest.

regards

 

[zuhairhaider]

Dear Damir & Ivo.maenen

Thx a lot for ur suggestion.I will try this out too.
Take care.

Regards

 

[zuhairhaider]

Dear Terry,
Thx for ur Ladder,I will try all those and as soon as i got the result i will be informing u all.

 

[zuhairhaider]

Dear Rsdoran,
Thx and i will try this out.

Take care.
regards.

 

[adner]

Hi,

I don't understand your problem. Why you are not able to draw ladder program? It's some software problem or you don't know how does Step7 Micro/Win works?

 

[zuhairhaider]

Dear Adner,
Actually I was unable to start the problem, but as i got some hints from all of u I will try and soon let u know.
Take care.

Regards

 

[ivo.maenen]

You can also use an edge detection to detect the end of e.g. T1 and use this edge detection to start e.g. T2 ect.