Alternator in FBD

kallileo · Oct 10, 2013

I know 2-3 ways of creating a simple alternator (toggle bit) in ladder but I'm not very familiar with FBD. In Zeliosoft FBD there a BISTABLE block which is practically an alternator but this block it's not present in all programming software.
Is there any other ways of creating an alternator using simple FBD blocks?

Mark- · Oct 10, 2013

Hello,

Yes.

kallileo · Oct 10, 2013

Thanks Mark.

As far as I understand when Enabled this circuit will produce at the output a signal with frequency set by Off Pulse Length+On Pulse Length. Is it correct?

I would like to alternate the state of the output everytime I press a push button. Like a T Flip Flop. First the output is False, when I press the button it goes True, when I press it again goes False and so on.

Mark- · Oct 10, 2013

Hello,

>As far as I understand when Enabled this circuit will produce at the output a signal with frequency set by Off Pulse Length+On Pulse Length. Is it correct?

No. The on pulse and off pulse length are defined by the pulse length value. If they are equal you have a square wave when enabled is true.
If the values are not equal then you get the on pulse length at X time and the off pulse length at Y time.

>when I press the button it goes True, when I press it again goes False and so on.

I misunderstood. When you said "alternate" I thought you wanted a pulsing output.

Now I see you just want a flip-flop. Designing the circuit should not take too long. Experiment.

kallileo · Oct 10, 2013

Seems pretty confusing in FBD...

Mark- · Oct 10, 2013

Hello,

This should work, untested.

dimmarkov · Oct 11, 2013

One possible way is this:View attachment T Flip Flop in FBD.bmp.

kallileo · Oct 11, 2013

Thank you guys.
Both solutions work perfectly but can't be implemented in Zelio Soft as there isn't (not sure) a positive/negative edge detection.

@Mark
It's just a electronic circuit of real life (almost) T Flip Flop.

Mark- · Oct 11, 2013

Hi,

>positive/negative detection.

I think it does, Blinker...

kallileo · Oct 11, 2013

Isn't Blinker just an input which alternate each second?
I don't think it's useful for either of the circuits.

Mark- · Oct 11, 2013

Hi,

I thought it was an edge triggered one-shot, I could be wrong. I do not have the documents.

kallileo · Oct 11, 2013

Found it.
Block TIMER BW (Pulses on Edges).

Thanks

hagos · Oct 21, 2013

One Shot

Dear folks,

Even if the PLC doesn't have one shot instruction, you still can program it your own:

-----I I----I/I------------( )

-----I/I-------------------( )

The first rung consists of the input andded to an inverted internal e.g a marker, the output is a one shot rising.

The second rung is the inverted input the out put is the internal (marker)

Cheers
Hagos

Alternator in FBD

kallileo

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Mark-

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kallileo

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Mark-

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kallileo

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Mark-

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kallileo

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