PLC Program

[Chris Corkhill]

Program

Hi Stu

please see attached. I have renamed the start sequence as this indeed is the door switch, as when door closes the sequence begins. I'm sort of confident in the program until rung 6, where the amber light is required to come back on for a further 10seconds, this is the point that I'm getting confused. Any suggestions would be appreciated.

Cheers

Chris

 

[Mrslipmat]

Will this actually run at all Looking at rung 1.... How does it latch in ?

Regards

 

[silva.foxx]

Ok Chris... as others here have stated, you are using 'outputs' twice in your program. Use the 'output' only once but utilise the 'OR' condition to switch the 'output' as desired.

Also, be cautious of using ]/[ conditions alone for a rung, such as in rung 8... your green lamp will be on full time. So will your amber lamp.

Door switch; what will not happen when you open the door?

Hint: to be able to utilise an 'output' more than once, have just one of said 'output' in your ladder but use the OR instruction as required.

|          Warning              

|          start              Y0

|--      +---] [---+----------( )- Amber lamp

|        |         |

|        | Warning |

|        | end     |

|        +---] [---+

|                             Y1

|--                          -( )- Red lamp

|

|                             Y2

|--                          -( )- Green lamp

Have you created a timing diagram such as:

|-----+                              +----------+

|     |                              |          |

|     +------------------------------+          +---------------|  Amber lamp (warning)

|

|     +------------------------------+

|     |                              |

|-----+                              +----------+---------------|  Red lamp (heating/danger)

|

|                                               +---------------|  

|                                               |               |

|-----------------------------------------------+               |  Green lamp (safe) 

 

[silva.foxx]

CC

Demo Mitsi software can be downloaded here: http://forums.mrplc.com/index.php?app=downloads&showfile=526

 

[Chris Corkhill]

Silva.foxx

Cheers for the advise, I will revise program and re-post for comments.

Chris

 

[Chris Corkhill]

Program

silva.foxx

please see attached, i have removed the latch from the door switch as i realised that opening the door would not stop the sequence.

see what you think, im not sure how to recall the yo (amber) light output as the second time i need it requires a different time sequence i.e 10 secs as opposed to 5 secs ??

Cheers

CC

 

[bernie_carlton]

At the first point where you have 'Y0' instead place M3 (or some other free control bit. At other points where you would want to place 'Y0' instead place a DIFFERENT 'M' bit. Finally, near the end of the program, place each of these 'M' bits in parallel with 'Y0' as the output.

 

  Condition                               M3

----] [-----------------------------------( )

 

Another Condition                         M4

----] [-----------------------------------( )

 

Yet another condition                     M5

----] [-----------------------------------( )

 

    M3                                    Y0

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

           |

    M4     |

----] [----+

           |

    M5     |

----] [----+

 

 

[silva.foxx]

CC... It's really clear that you are making a great effort with your problem. :nodi:

Rung 2: where has X2 appeared from and what is it?

Your amber lamp will remain on as long as M1 is high.

Your red lamp will be on for 5 seconds (from M1 going high) as M2 will never be on long enough to complete the T2 time.

What is the branch around M2 in Rung 5?

Rung 6: X2 (again)? M3? Where's T3 doing it's stuff?

Rung 7 & 8: ***DOUBLE COIL***

 

[Chris Corkhill]

silva.foxx

back to drawing board, keep checking I'll post a revised version, once i've buried my head in some more books

appreciate you guidance, cheers

Chris

 

[Chris Corkhill]

silval.foxx

x2 is my OR function.... to recall the amber light ??

why will amber remain on when its on a timer ??

I dont understand why M1 has a bearing on M2? M2 is timed 30 secs

T3 is trying to recall amber light for 10 secs

double coil i will rectify ....

chris

 

[Chris Corkhill]

ive seen this done in other programs, what is the difference ?? is it a more simplified way ??

Cheers

Chris

 

[gbradley]

Look again at Bernie's example.
Post #37


You really need to understand that concept.
Pardon the pun, but the light will go on soon.

 

[Chris Corkhill]

Program

get what you mean just having trouble with recalling the amber lamp twice

chris

 

[L D[AR2P#0.0]]

How do these timers function - a rising edge on the input to the coil gives a pulse of the specified time ?

 

[silva.foxx]

silval.foxx

x2 is my OR function.... to recall the amber light ??

why will amber remain on when its on a timer ??

I dont understand why M1 has a bearing on M2? M2 is timed 30 secs

T3 is trying to recall amber light for 10 secs

double coil i will rectify ....

chris

Hey up Chris... wrt post #36

X2 will be an input... so what's the input?

Your amber lamp will remain on because M1 will remain on as long as the doorswitch and stop remain intact.

In rung 3 T1 will stop M2 from going high after 5 secs.

T3 has no 'contact' anywhere?


DO NOT LOSE HEART WITH THIS! You will understand very soon. I really want to see you do this.


wrt post #43

you can use only one output for the amber lamp... look at rungs 9 and 11 and what you have done... then combine them... ie...

  m1

--] [---+----------------------(Y0) amber lamp

  m3    |

--] [---+

Now lets rip your ladder to bits!

Rung 1: enables M1 to go high and remains so until the doorswitch is opened or stop pressed (assuming stop is a n/c button)

Rung 2: M1 enables T1 to time

Rung 3: enables M2 to go high until T1 times out after 5 secs so your red lamp will light.

Rung 4: M2 will not be on long enough for T2 to time.

Rung 5: M3 will never go high as T2 will never go high.

Rung 6: I'll not go any further!

Download this link: http://forums.mrplc.com/index.php?app=downloads&showfile=416

@ L D[AR2,P#0.0] whilst the timer input is high the timer is in action but is reset if the timer input goes low.