PLC Knightrider programme?

[gnccollege]

Hi Guys.

Im Programming a knightrider beam light using GX Developer on 8 leds flashing from Y0 to Y7 and back.

Anybody know how to do that?

i have done half the programme where leds are flashing from Y0 to Y7 but i dont know how to go back from Y7 to Y0. the programme also has to run forever until switched off.

I have started with T0 with Y0 as output and timer of T0 K5 and then i closed the loop with T0. this turn on Y0 for 0.5 second and move on to next output. i have done all my steps same like this. I just dont know how to go back from Y7 to Y0.

Pls give clear instructions as im new to plc.

Thanks
Ron.

 

[xnuke]

Is this for school?

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[gnccollege]

No its not an assignment. im just doing it bcos i want to learn basic plc programming.

 

[jraef]

A lot will depend on the programming capabilities of your PLC, they are not all created equal. How did you do the half you already figured out?

"Will work for (the memory of) salami"

 

[waross]

One solution in Boolean:
Start with a shift register with enough steps to handle all the states, Y0-Y7-Y0
Initialize the register with one flip-flop set (1).
Connect the register tail to head. Step the register with your timer.
Now the one bit should travel around the register.
The first step will use a one shot to turn on Y1.
The second step will use a one shot to turn on Y2.
.....................
The seventh step will use a one shot to turn off Y7.
The eighth step will use a one shot to turn off Y6.
Continue.
Another alternative is to use a variation of a switch-tail ring counter. Assignment; Research switch tail ring counter. It has been called a bi-quinary counter when used for counting in base ten systems.


Bill
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"Why not the best?"
Jimmy Carter