Old Geezer needs Tutoring Nudge

[promanen]

OKEY DOKEY , I've got most of the Ladders operating in Manual Mode and I used Latching and Unlatching modifiers.
Now I am supposed to add a flashing light to my circuit when the door goes down.
Problem ... I cannot find any reference in Phil's " HOW TO BOOK " to set up a flashing circuit.
Are you ready for my completed circuit to date for constructive critism ?
Pete

 

[Ken Moore]

Some PLC's have built in flashing bits, others don't.
To build your own flashing circuit, there are several options.

1. Use two timers, one for the off time, and one for the on time, each timer resets the other.
2. Use one timer and a compare or limit test on the accumaltor value.
3. Use one timer to drive a flip-flop circuit.

I'm sure there are others, but these three are the ones I've seen most often.

Didn't want to give you to much, since your trying to learn as you go, but I can post an example if you need one.


Ken

 

[promanen]

Some PLC's have built in flashing bits, others don't.
To build your own flashing circuit, there are several options.

1. Use two timers, one for the off time, and one for the on time, each timer resets the other.
2. Use one timer and a compare or limit test on the accumaltor value.
3. Use one timer to drive a flip-flop circuit.

I'm sure there are others, but these three are the ones I've seen most often.

Didn't want to give you to much, since your trying to learn as you go, but I can post an example if you need one.


Ken

option 2 and 3 are the ones I have not been exposed to . Therefore it sounds like Greek to me.
Do you have any rung examples of them ?
Thanks for the assistance

Pete

 

[rsdoran]

Look here http://www.patchn.com/ab_plc_flasher.htm

 

[Ken Moore]

Ron's link covers option 1 & 2, see attached photo for option 3.

 

[castlerock]

Thank you for that bit of code Ken. You thought me somthing.

 

[promanen]

RSDORAN and Ken

Thank You. I will now attempt one of two succesful DEEDS.

I will correctly insert it into the proper RUNG or I will chop down a Cherry Tree and throw it across the Potomac

Pete

 

[castlerock]

Thank you for that bit of code Ken. You thought me somthing.

er...taught me somthing.

 

[Lancie1]

Pete,

Your LogixPro simulator DOES have a "flashing bit", actually several of them. They are located at S:4/0 up to S:4/15 (same as in Allen-Bradley SLC's). I use S:4/7 a lot, as it flashes at a useful rate for human eyesight.

Latch and Unlatch are not the preferred instructions to use for controlling motor outputs. Sure they will work, but their use in latching on a motor could be dangerous in the real world. What would happen for example, if you had a PLC actually controlling a door opener, and you started the door down, and then lost power to the controls? While the power is off, you decide to back the car up to do some work on the engine. Then the power comes back on, and because the motor was still latched, the door rolls down onto the top of your car!

 

[promanen]

Finally got the " Bloody thing to work "
Thanks to all of you... and " no thanks " to the academic elitist at....

Here is a wiring diagram homework from 1995 at the Tech College I attended. I'm now trying to PLC Logic a program for it.
The electrical rung # 3 with a branch leg to SS1 is a booger on my logic program.
When I attmept to get PB 3 conditions to respond to the truth table on the wiring diagram I cannot simulate the same condition
Any suggestions ?

Pete

 

[timL]

Would you mind to share your final ladder program here for public enjoyment as another success story?

 

[rsdoran]

I am not sure what happened but the "TRUTH TABLE" per se WILL not match the relay circuit. .
In order:
PB-1 Momentarily activated Light 1 OFF Light 2 ON Light 3 OFF YES
PB 2 Momentarily activated Light 1 ON Light 2 ON Light 3 OFF YES
PB 4 Momentarily activated Light 1 ON Light 2 ON Light 3 OFF YES
CR2 is not on therefore CR3 nor L3 will turn on.
PB 3 Momentarily activated Light 1 OFF Light 2 OFF Light 3 OFF NO
Here it goes awry, CR2 is energized and Light 2 will come on but Light 1 stays ON because CR2 is not part of the "holding" circuit.
PB 2 Momentarily activated Light 1 OFF Light 2 OFF Light 3 OFF NO
PB2 will do nothing because CR1 and Light 1 are already ON.
PB 4 Momentarily activated Light 1 ON Light 2 OFF Light 3 ON YES but not in the manner I think they expect it to turn the lights on..as noted CR1/Light1 came one when PB2 was pressed...only PB1 can turn it off therefore with CR2 enegized then PB4 could energize CR3 and Light 3.
SS-1 Momentarily activated Light 1 OFF Light 2 OFF Light 3 OFF
Once CR1 is turned on only PB1 can turn it off, hence L1 will be ON as long as CR1 is ON, the same applies to CR2....ie the only thing SS-1 will turn off is CR3/L3.

I have attached a pdf of the diagram converted to an AB program. Technically using a plc you could branch L1 (light1) under CR1 and L3 under CR3.

 

[promanen]

If I read the posts correctly the majority of the membership does not condone the posting of the final project. This is a learning site and while the members will help those who submit their drawing for analysis they do not post the solution. Therefore , in the spirit of those members I will not post the final drawing.
However , this site gave me more from making me sweat the answer than from giving me the answer.

Pete

 

[promanen]

One " Dummie " question ; under your XIC - XIO symbols you have notations " 1761-micro " What are those for ?

Pete

 

[Rube]

Promanen--



RSLogix put those notations there, he didn't.