a little strange doubt question

[crying_baby]

hello, its me again>> i had been cracking my skull figuring out y the outlet valve is related by f1, f2 and f6 while the rest of the state is related to the inlet valve. can som1 plz explain me this.. i cant ask my lectuer as he gave notice that he is not xpert in this area so he dunno anithing..

what i have now is teh forum to answer my doubts (hopefully) Respect



the flowchart is designed for the ladder attached. but y does the last 2 rungs relates to teh 3 state each. i cant find the reason y>> plz enlighten me!!

 

[bernie_carlton]

Each state (F1 - F6) has exactly one valve open and one valve closed.

F1 - Outlet valve open, Inlet valve closed
F2 - Same as F1 - no change yet
F3 - Outlet valve closed, Inlet valve open
F4 - Same as F3 - no change yet
F5 - Same as F3 - no change yet
F6 - Outlet valve open, Inlet valve closed

Then the flow chart returns to F1 which has the same valve conditions as F6

So, rewritten as valve open states

Outlet valve - F1, F2, F6
Inlet valve - F3, F4, F5

 

[DFJ]

Project

The outputs at the top of the ladder logic are just internal I/O for the Real I/O at the bottom. Therefor the two rungs at the bottom are just a result of the conditions at the top. The onlt to real world outputs are the two outputs to open and close the valve.

 

[crying_baby]

Each state (F1 - F6) has exactly one valve open and one valve closed.

F1 - Outlet valve open, Inlet valve closed
F2 - Same as F1 - no change yet
F3 - Outlet valve closed, Inlet valve open
F4 - Same as F3 - no change yet
F5 - Same as F3 - no change yet
F6 - Outlet valve open, Inlet valve closed

Then the flow chart returns to F1 which has the same valve conditions as F6

So, rewritten as valve open states

Outlet valve - F1, F2, F6
Inlet valve - F3, F4, F5

The outputs at the top of the ladder logic are just internal I/O for the Real I/O at the bottom. Therefor the two rungs at the bottom are just a result of the conditions at the top. The onlt to real world outputs are the two outputs to open and close the valve.

thank u very much. now i understand
haf a nice day!!!

 

[crying_baby]

hello, 1 more question is that, physically, the outlet and inlet valves are the only physical real world output ,.. therefore i can use teh internal memory address ( such as %m001, %m002 etc for gefanuc or b2/1 b2/2 etc for omron cxprogrammer )of the PLC for f1,f2,f3 etc and the transition states for t1, t2 etc in the ladder.. practically, thats what we do during implementing teh PLC code am i right

plz enlighten me. thank u!!

 

[bernie_carlton]

A typical system also references input devices. Your flow chart mentions the button and (by inference) a 'full tank' sensor. Presumeably some other logic will be performing the logic decisions (represented in the flowchart as diamonds) using these inputs and the states (F1 - F6) to produce the transition triggers (T1 etc).

 

[crying_baby]

A typical system also references input devices. Your flow chart mentions the button and (by inference) a 'full tank' sensor. Presumeably some other logic will be performing the logic decisions (represented in the flowchart as diamonds) using these inputs and the states (F1 - F6) to produce the transition triggers (T1 etc).

thank u bernie for ur kind explanation . sry for being vague. i mean the transitions t1,t2 and f2,f1 etc i can assign them to internal PLC memory address since these r assigned based on my flowchart states,

the sensors etc ya that'll assigned external output relays

plz enlighten me further as i trying to implement the hardware on this onto omron ^^

 

[crying_baby]

bernie this solution is it logical since it doesnt use any of the input sensors like FULL tank and STOP pbutton?

is it still possible or is this ladder missing or incomplete?

 

[bernie_carlton]

I had assumed that you wer only showing part of a larger ladder logic diagram. Therefore, as I stated, I also assumed that the derivation of the state transition triggers from the start and stop buttons and 'tank full' inputs was being performed elsewhere in this larger diagram. Is the ladder diagram one you created or has it been given to you as it is to analyse? It may help to understand what the target PLC is.

 

[crying_baby]

ya this isthe approach to use flowchart to design the ladder. but there isnt another part of the program. actually, this ladder is translated directly by teh flowchart.

i find it just cant implement the hardware of this PLC tho.

there are other example in this book that use this method to convert flowchart into ladders, but odd the input triggers r hidden .

i'll go try this ladder in the labs and see what happen.

thank u bernie

 

[crying_baby]

hello, 1 more question is that, from the ladder diagram, all the outputs are put at the bottom of the ladder. is this a style by experienced PLC guru to put al the outputs at the end of the ladders, or is it just a coincident in this case.

plz enlighten me! ima goin to campus now ^^^

 

[bernie_carlton]

I have a feeling that the ladder which you presented is more of a suggestion as to the flow of logic and is not meant to be an actual functioning program. I have a feeling you are going to have a lot of work ahead of you. Fortunately, this is the kind of work where every mistake helps you learn.

 

[crying_baby]

ok i see what i can come out wif

thank u very much bernie