ladder logic

nazeeravt · Apr 26, 2012

I am finding it difficult to solve this problem,the question is:
I have 5 led's
led 1
led 2
led 3
led 4
led 5

in the increasing order the led's should glow and each time only one led should be glowing serially from 1 to 5. Again the led's should start in reverse order i.e
from 5 to 1 and this should be continuous.

I have solved 1-5 and again 1-5 continuously but not 1-5 , 5-1.

Thanks

KalleOlsen · Apr 26, 2012

Post the code you've developed, and the guys who know your PLC type (cant be a secret, or?) will most certainly help you.

Kalle

nazeeravt · Apr 26, 2012

two plcs are available siemens s7 200 and allenbradley micrologix 1000.I can convert one from the other.For siemens step 7 microwin 32 and micrologix 500 for allenbradley.

widelto · Apr 26, 2012

Use SQO and a .DN of timer as follows:
10000
01000
00100
00010
00001
00010
00100
01000

Then repeat sequence.

KalleOlsen · Apr 26, 2012

nazeeravt said:
two plcs are available siemens s7 200 and allenbradley micrologix 1000.I can convert one from the other.For siemens step 7 microwin 32 and micrologix 500 for allenbradley.

And what have you programmed so far?

Kalle

fredz0003 · Apr 26, 2012

Hi I am a beginner plc programmer as well but the way I would do it, is using counters and timers,
if counter = 1 then turn on light 1 after the timer is done, then increase the counter by 1.
if counter =2 then turn on light 2, you get the picture.
When you get to the last light instead of increasing the counter decrease it. I haven't messed with seq but this is pretty easy with counters and timers I think.

KalleOlsen · Apr 26, 2012

What the OP has asked for is very, very basic programming.
Would be interesting to see how/what he has done so far, before he gets a multiple of dozens different suggestions from us others

.

Kalle

Lancie1 · Apr 26, 2012

Nazeeravt,

Here is a sequencer method to do 1-5 then 5-1, apparently left over from your instructor's class last year. This one has variable time steps too, but maybe he decided that was just too difficult. It should be easy for an experienced student like yourself to figure out how to reverse the sequencer pattern numbers.

Some of the last two rungs got cut off by my PDF printer, but you should have enough to see the method!

fredz0003 · Apr 26, 2012

KalleOlsen said:
What the OP has asked for is very, very basic programming.
Would be interesting to see how/what he has done so far, before he gets a multiple of dozens different suggestions from us others .

Kalle

I am with you on that, but with my suggestion he still gotta know how to use timers, and counters.

nazeeravt · Apr 27, 2012

THANKS
I will make an attempt

Nigasai · Apr 27, 2012

this is a very easy code.. You only need CTU and CTD with same Address, a pulser series with directional bit xic (Down if on, count up if off) then trigger your Counter up, Next CTD or Counter down with pulser series with Directional Bit xio in off ..

dahnuguy · Apr 27, 2012

insert spoon

I wonder of these instructors are giving the students enough time to figure this stuff out or if they are not starting until it is too late?

As for the assignment,

I suppose you have to use a timer in order to see the LEDs change state.

Try using just one timer.

A counter might be a good way to go, but I would increment an INTeger.

Maybe like a use case, or a simple if then

The only trick here is that you need to "remember" that you have already counted UP to 5 and then you need to count down.

One section will count up, then you get to 5, how do you "remember" that you have already counted UP and should now count down?

That is the thing he is adding to this assignment versus the previous.

I am sure he mentioned this.

There are several ways to do it. In Siemens there are probably at least 100.

VAN · Apr 27, 2012

I may not have followed the question correctly, but why count down at all? I mean you can but it sounds potentially harder.

0 - none
1 - 1
2 - 2
3 - 3
4 - 4
5 - 5
6 - 4
7 - 3
8 - 2
9 - 1
(RST)

Just use a count up and have the outputs run on OR statements. (There are a lot of ways to solve this though.)

CheezyMane13 · Apr 27, 2012

Using one CTU and one CTD that is triggered by the DN bit of the CTU, set both to only count to 5 of from 5. a equal than command to trigger each LED at given number, when the counter get to each number the corresponding LED should light up

Lancie1 · Apr 27, 2012

Using one CTU and one CTD that is triggered by the DN bit of the CTU....

Cheezy, Something like this Allen Bradley MicroLogix 1000 program?

ladder logic

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