PLC Program

[shoelesscraig]

Andy6, can only see the bottom rung ?

Wow, you're quick...that was the whole point.

People on this forum don't like people who make smart *** remarks such as not requiring "lessons on morality". If you don't want responses like Andy's, then don't come on here wanting your work done for you. And if you DO want me to do it for you, let me get you an account number to wire the money to first...

 

[Chris Corkhill]

Silva.Foxx

The oven is to be heated up to a nominal 80degC, the alarm conditions and interlock would be if oven door opens during heating then the whole process would stop. I have attempted a program which i have posted on here in pdf, but I'm unsure its correct.

 

[nehpets]

The way I see it all you will be doing is turning on the red light for 5seconds, where are the internal flags M2 & M3 actioned?

Steve

 

[Chris Corkhill]

The amber light should be on for 5 seconds, then when this timer drops out the red light on for 30, this is where im struggling to be honest, with the timers etc

 

[sthompson]

The amber light should be on for 5 seconds, then when this timer drops out the red light on for 30, this is where im struggling to be honest, with the timers etc

What Nephets was asking is where are the Coils for the Internal M2 and M3 Contacts?

Stu....

 

[Chris Corkhill]

Im with you now, is it a case then of almost replicating the first rung showing the coil as the output before the timer coil ?

 

[sthompson]

Im with you now, is it a case then of almost replicating the first rung showing the coil as the output before the timer coil ?

Well, you will have to make those decisions. However, I will give you a couple of suggestions. I am not familiar with the Mitsubishi PLCs, but you have two Y0 Outputs for the Amber Light, which usually isn't a good thing.

You have an M2 and M3 Contact with no Coil to operate them. What are they supposed to be doing?

Where is your Oven at Temperature detection, or are you just going on time?

T1 should be affecting the Amber Light Output Y0.

T2 should be affecting the Red Light Output Y1.

You are going to need another Timer for the Amber Light since you operate it twice, and a 15 Second Timer for your Green Light.

Revise your Program and re-post it.

Stu.....

 

[Chris Corkhill]

The oven is just running on time, i will revise and re-post ...

Cheers

Chris

 

[Chris Corkhill]

Revised program

second attemp, i'm not sure how to use the YO (amber light) output twice ??

 

[jvdcande]

second attemp, i'm not sure how to use the YO (amber light) output twice ??

Search the site for "double coil syndrome". The answer is here to find.

Regards,

 

[Chris Corkhill]

Program

Hi

Please could you check this program and post comments if possible. Im not sure if I'm heading in the right direction, I'm struggling a bit with using the same (YO) output twice for the amber light, is this possible ?

Cheers

Chris

 

[OkiePC]

I'm struggling a bit with using the same (YO) output twice for the amber light, is this possible ?

Yes, it's possible, but no, it won't work...
(Typically) the PLC program will update the internal address holding the state for the YO address whenever it encounters a rung that modifies the state. Then, at the end of the program, it will send that state to the actual output point, so the "last rung wins" rule applies, meaning the last bit of logic before the I/O updates will be in control of the attached device. There are some PLCs that update the I/O asynchronous to the program scan. With that type of PLC, the state of the real output becomes unpredictable. I don't know Mitsubishi PLCs so I am not sure whether your logic will follow the "last rung wins" rule or simply be erratic.

In either case, you should combine all of the rungs which need to control that output into one rung.

 

[silva.foxx]

  

 Start

 Sequence   Stop

|--] [----+--] [-------------------------------(M1)-  Door switch

|         |                       

|         |

|  M1     |

|--] [----+

|

|

|  M1                                          K50

|--] [-----------------------------------------(T1)-  5sec timer

|

|

|

|  M1

|--] [-----------------------------------------(Y0)-  Amber lamp

|

|

|

|  M1       T1

|--] [---+--]/[--------------------------------(M2)-  Red lamp coil

|        |

|        |

|  M2    |

|--] [---+

|

|

|

|  M2                                          K300

|--] [-----------------------------------------(T2)-  30sec timer

|

|

|

|  M2       T2

|--] [---+--]/[--------------------------------(Y1)-  Red lamp

|        |

|        |

|  M3    |

|--] [---+

|

|

|  T2

|--]/[-----------------------------------------(Y0)-  Amber lamp (again)

|

|

|  M1                                          K100

|--] [-----------------------------------------(T3)-  10sec timer

|

|

|  M3

|--] [-----------------------------------------(M3)-  Green lamp coil

|

|

|  M3                                          K150

|--] [-----------------------------------------(T4)-  15sec timer

|

|

|  T4

|--]/[-----------------------------------------(Y2)-  Green lamp

|

|

|

|---------------------------------------------(END)- 

 

So... you have no doorswitch... how does the system know that the door is closed?

On setting M1... list everything that is shown in your program that will 'energise' when M1 goes high...

When will M3 go high?

Do you think all these lamps will light at the same time?

On a positive note... you are showing great effort.

 

[Chris Corkhill]

hi, i have produced another version of program and will post soon

cheers

 

[Chris Corkhill]

Program

Silva.foxx

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