RSLogix 5000 Creating a Triangle pulse Ladder Logic

1010101

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Hi Guys,

I am trying to create a triangle (Sawtooth) pulse in RSlogix 5000 using counters/timers and anything else. I'm not sure what the ladder logic would look like.
 
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A little more info on what you are trying to control might help.

You are not going to get a digital output to do anything but a square wave.

To get a sawtooth you are going to have to use a analog output. IMHO.

What is the frequency of this sawtooth pulse?
 
Its one of our labs for Industrial Automation. We created a flasher program on RSlogix5000 (1756 ControlLogix)and are suppose to modify the ladder logic to generate a triangle waveform. There is no given frequency or criteria to meet other then it being a triangle pulse.
Like the wave of a timer but with a smooth line instead of steps.
post-19234-0-08233300-1322823636_thumb.png




Would looking at my flasher.ACD file help?
 
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I'm not a RSLogix5000 user so hopefully someone that is will take a look.
You are better off zipping the file and post that here.
 
Which do you need? A triangle wave or a sawtooth one? (they are different).

For a sawtooth, just plot the .ACC value of a free-running timer. Done.

XIO Timer.DN TON Timer 1000 0
 
rdrast said:
Which do you need? A triangle wave or a sawtooth one? (they are different).

For a sawtooth, just plot the .ACC value of a free-running timer. Done.

XIO Timer.DN TON Timer 1000 0
Click to expand...

Hi rdast, I need a triangle wave. The .ACC value of the timer plots a sawtooth wave but the side of the wave isn't linear. It looks like a step function. It goes up levels off, goes up levels off.
Sorry if I am not doing a very good job explaining.
 
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In the end the analog output will have steps equal to the change of the least significant bit. If you are somehow hoping for absolutely smooth the PLC analog output isn't your answer.

Even plotting an internal number can't give you an absolutely smooth waveform. There will be a point at which the number changes then a finite amount of time before it changes again.

You will just have to refine it until it is "smooth enough".
 
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My goal is to create a wave like this.
fbhviCB.jpg


Thank you for the response bernie. I understand that I need to refine the waveform until it is smooth enough. So if I plotted the .ACC value of my timer how do I refine it enough to look like the above wave. if that is possible

I was thinking once I get that sloped side I can just reverse the ladder logic for the run then copy/paste it to form the other half of the wave.
 
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I was thinking once I get that sloped side I can just reverse the ladder logic for the run then copy/paste it to form the other half of the wave.
Click to expand...
For the wave form between t2 to t3, use the formula t2 Maximum Value - t3 time, with a limit of 0. This will give you a negative slope going downhill from t2 max to 0.
 
Search the forum for ramp. There are lots of analog output ramping programs that have been posted. You need a ramp up and a ramp down, once you understand how to do a ramp the rest is trivial.
 
Lancie1 said:
For the wave form between t2 to t3, use the formula t2 Maximum Value - t3 time, with a limit of 0. This will give you a negative slope going downhill from t2 max to 0.
Click to expand...

TConnolly said:
Search the forum for ramp. There are lots of analog output ramping programs that have been posted. You need a ramp up and a ramp down, once you understand how to do a ramp the rest is trivial.
Click to expand...

Ok Thanks for the responses. I am going to search the forum and see if I can get it working later when I get to class.
 
1010101 said:
Ok Thanks for the responses. I am going to search the forum and see if I can get it working later when I get to class.
Click to expand...

It could be as simple as adding a small value to a register on each sweep, and then subtracting that same value from the register once you have reached a preset maximum value.
 

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