ladder help

[rootboy]

Click the "Go Advanced" button, then enter your ladder logic, hightlight (select) it, then click the "| | ABC Ladder" button to freeze it as is, then Save Changes. You must not edit it again, or it will revert to a jumbled mess.

Okay, thanks. So it was because I edited it after selecting the tags.

 

[rootboy]

all too familiar for me too haha. another one i had was a guy arguing with me that you have to use 3 wire to wire a 3way. now i agree that 3wire method is better, however you can do it in a 3wire. i learned that renovating an old home, back before they had 3wire. i call it the pyramid technique.

Years ago, I worked for an Electrical shop in Colorado Springs, CO which was run by the old man and his son.

Gary (the son) didn't have much - if any - electrical experience and was finishing off his basement at home. So he asked me if I would come over on a weekend and help him out. Gary was a nice enough guy, so sure, why not?

Gary showed me what he wanted (including five three-way circuits) and then told me that he needed to go upstairs for a moment and would be right back. He went upstairs and that was the last that I saw of him until the end of the day.

Okay, nice guy or not, he was taking advantage of me.

Paybacks being what they are, a female dog, I wired each of his three-way circuits a different way. I showed him what I had done after I had finished and then had to draw out each circuit to prove to him that it would work.

I essentially put him in the position of having to hire an electrician to fix his own house.


In these examples the switch leg goes to the light fixture. And when I mention "power", I'm referring to the "hot" and a neutral being fed from the same breaker (in other words the same circuit throughout)

"Normal" 3-way. Power on one end, switch leg on the other, three conductor w/ground in between

Dead-end 3-way. Power and switch leg at the same end, three conductor (w/gnd) goes to other switch


Kinda oddball example.

Power in the light fixture, with a three conductor going to each switch.


Legal in some states (Colorado, for example). Not advised.

Power in each switch, switch leg to light fixture, two conductor w/gnd to other switch.

Power in one switch and light fixture. Two conductor to light from one switch, three conductor from other switch to light.

 

[dahnuguy]

Xor

 

[CheezyMane13]

Hey Lancie
While your in the teaching mode....
How do you use the bldy '+Quote'

You must be asking about the Multi-Quote feature. Don't ask me, I don't know and have not been able to figure it out.

To do a multi quote you simply hit the +quote button on all the quotes you want to insert into your post. Then on the last quote you hit the regular quote button. POOF there you have all the quotes in one post and you can reply back to all of them at once.

 

[KalleOlsen]

And in Step7 one could do it like this (32 switches). It will flop or flip every time a switch is moved.

L IDx // Load input double word
L MD10 // Mask out unwanted inputs
AD
L MD14 // Old masked input status
TAK
T MD14 // Store masked input status
XOD // xor relevant input status
SAVE
X BR // Flippeti...
X LAMP // ...flop
= LAMP
= not tested

Kalle

 

[dahnuguy]

Hamming Weight

Hey this is the example of using the Hamming Weight in a machine I was looking for earlier!

If the Hamming Weight is greater than one,
then error.

If the Hamming Weight is equal to one, then continue with operation.

This way you can compare a long list of booleans and XOR them all together.

 

[TConnolly]

With switches 1 and 3 ON, Tim's interlock would look like the attached picture.

I think Tim meant this to be the Boolean equation:

(SW1*(SW2+SW3)) + (SW2 * SW3)

That's what I get for doing this in a hurry on Friday after its time to go home. + is OR and * is AND

The corrected Boolean equations from the truth table are

Interlock = (SW1 * SW2) + (SW1 * SW3) + (SW2 * SW3) + (SW1 * SW2 * S3)

Simplifies to
Interlock = (SW1*(SW2 + S3)) + (SW2 * SW3)

Light = (SW1 + SW2 + SW3) * NOT Interlock.

(Note: This isn't the solution to the OP since additional information was provided - I'm just correcting the boolean operators I posted earlier in case someone refers to this in the future.)

 

[TConnolly]

Since we are simulating 3-way and 4-way light switches then we can apply the same truth table techniques.

The truth table for two two way switches is

A  B  X    

0  0  0    

1  0  1    

0  1  1    

1  1  0

The Boolean equation is X = (A*NOTB)+ (NOTA*B)
(mentioned above)


To add a third switch to emulate a 4-way light switch the truth table becomes

A  B  C  X

0  0  0  0

1  0  0  1

0  1  0  1

1  1  0  0

0  0  1  1

1  0  1  0

0  1  1  0

1  1  1  1

And the Boolean Equation is

X = (A*NOTB*NOTC) + (NOTA*B*NOTC) + (NOTA*NOTB*C) + (A*B*C)

Even though we can simplify this expression, at this point I would code it as is because the extra branches won't simplify the the actual code mnemonics, but since this is a class exercise we should probably simplify the Boolean expression.

X = A*((NOTB*NOTC)+(B*C)) + NOTA*((B*NOTC)+(NOTB*C))

This solution is also shown above. Hopefully now you can see how to arrive at that point, and if the teacher asks you to add yet another switch you could do it.

 

[TConnolly]

To code the expression X = (A*NOTB*NOTC) + (NOTA*B*NOTC) + (NOTA*NOTB*C) + (A*B*C) as is without simplifying

        A       B         C               X 

---+---] [-----]\[-------]\[----+--------( )

   |                            |

   |    A       B         C     |

   +---]\[-----] [-------]\[----+ 

   |                            |

   |    A       B         C     |

   +---]\[-----]\[-------] [----+      

   |                            |

   |    A       B         C     |

   +---] [-----] [-------] [----+                                

As you can see, even though the Boolean expression isn't simplified, sometimes the translation to ladder is simple because it avoids extra branches.

 

[Lancie1]

POOF there you have all the quotes in one post and you can reply back to all of them at once.

Thanks, Cheezy.

 

[dahnuguy]

To code the expression X = (A*NOTB*NOTC) + (NOTA*B*NOTC) + (NOTA*NOTB*C) + (A*B*C) as is without simplifying

        A       B         C               X 

---+---] [-----]\[-------]\[----+--------( )

   |                            |

   |    A       B         C     |

   +---]\[-----] [-------]\[----+ 

   |                            |

   |    A       B         C     |

   +---]\[-----]\[-------] [----+      

   |                            |

   |    A       B         C     |

   +---] [-----] [-------] [----+                                

As you can see, even though the Boolean expression isn't simplified, sometimes the translation to ladder is simple because it avoids extra branches.

Amen, I was beginning to wonder just how far this thread would go before someone came back to reality.

However, I will add that if you need to do this 32 times, it would be easier, simpler, and better to use the Hamming Weight and compare to 1.

Just imagine doing this same thing with 32 or 64 switches, the simple method is not scalable.

But for 3 switches, simple is good.