Write A Program for this Process

cattiebrie

Member
C
Join Date
Jul 2017
Location
Los Angeles
Posts
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Hi, I'm a returning student (over 10 years out of school) and I'm a little lost in my course. Can someone please come up with a program for this process? I want to use your answer in my LogixPro and see how it functions, that way I can learn from your answer.

Write a program to implement the process illustrated. The sequence of operation is to be as follows:
• Normally open start and normally closed stop pushbuttons are used to start and stop the process.
• When the start button is pressed, solenoid A energizes to start filling the tank.
• As the tank fills, the empty level sensor switch closes.
• When the tank is full, the full level sensor switch closes.
• Solenoid A is de-energized.
• The agitate motor starts automatically and runs for 3 min to mix the liquid.
• When the agitate motor stops, solenoid B is energized to empty the tank.
• When the tank is completely empty, the empty sensor switch opens to de-energize solenoid B.
• The start button is pressed to repeat the sequence.

HelpPlease.jpg
 
You can do it. Just work through the process. Best way to learn. Start your program and if you get stuck zip your logixpro ladder file, tell us what you need help with, and we'll help.
 
Last edited:
cattiebrie said:
Hi, I'm a returning student (over 10 years out of school) and I'm a little lost in my course. Can someone please come up with a program for this process? I want to use your answer in my LogixPro and see how it functions, that way I can learn from your answer.

Write a program to implement the process illustrated. The sequence of operation is to be as follows:
• Normally open start and normally closed stop pushbuttons are used to start and stop the process.
• When the start button is pressed, solenoid A energizes to start filling the tank.
• As the tank fills, the empty level sensor switch closes.
• When the tank is full, the full level sensor switch closes.
• Solenoid A is de-energized.
• The agitate motor starts automatically and runs for 3 min to mix the liquid.
• When the agitate motor stops, solenoid B is energized to empty the tank.
• When the tank is completely empty, the empty sensor switch opens to de-energize solenoid B.
• The start button is pressed to repeat the sequence.
Click to expand...
Check the Downloads section using the tab at the top of the page. In the Allen Bradley section there are a lot of RSLogixPro programs. Look thru them, one might be what you are looking for. I would write the program you described but others would object, saying that I was taking away your opportunity to learn. My preference is that I like to show by example just as you have requested.
 
Thank you for the tip jrwb4gbm, I will look through the Downloads section. Yes, I'm a person who learns through example. Its difficult for me to learn if I don't know if my answer is correct or not. My professor corrects my homework at the end of the week and that doesn't help me with the test which is in the same week. It would be too late.
 
Being an electrician first and a programmer second, whenever I have to create logic that might be tricky I always draw myself up a working electrical schematic with relay logic and pushbuttons. Once I'm able to do that, transferring that electrical schematic into Ladder logic is quite simple for me.

If this method isn't for you maybe try drawing out a SFC chart or even break it down into smaller sections of logic.

One thing I didn't see you mention was what is expected to happen if the stop button is pressed during Filling/agitating/emptying cycle?

Edit** as much as I'd love to draw this logic up for you, the best way to learn is to dive in and make mistakes, especially when working with homework assignments.
 
think of the process as steps

then think of what needs to happen to advance the step

pseudo code would be



'step actions
STEP EQU 10 THEN DO SOMTHING


step complete
STEP EQU 10 AND CONDITION THEN NEXT STEP =20


'advance step at end of scan
STEP=NEXT STEP
 
START_PB is N.O. so with a XIC (true if closed) instruction pressing it =1 which is right.

STOP_PB is N.C. so with a XIO (true if open) instruction it =0 right now, we need this to =1 in its natural (N.C) state and to =0 when you press it.

Then when you release the START_PB the process will stop. Gonna have to fix that.

I want to help you but this is really basic day 1 stuff. Do this, since you have logixpro, Go to HELP menu of logixpro, go to STUDENT EXERCISES and it will have all you need to know.

Then again the thought has crossed my mind your just messing with us.
 
You are on the right path, but you need to re-read the process description. You have the motor starting by pressing the Start button instead of the full level sensor. You will also need something to keep solenoid A energized after the start button is released. A quick Google of seal in, or holding logic will show you how to do that. I'll let you get that sorted out first, then we can move on from there. Keep posting screen shots as you go, and we can help you get to the finish.

Bubba.
 
cattiebrie said:
Its difficult for me to learn if I don't know if my answer is correct or not.
Click to expand...

This is something everyone in the forum will pitch in to help you with for sure, either to tell you where it is wrong and where it could be done differently or in a better way.

Everyone works differently, but perhaps listing what are the requirements for each device in the process to work can give you a list of what needs to be added to the controls of the device as well as logic that may need to be created such as level alarms and such.
 
plchris said:
Then again the thought has crossed my mind your just messing with us.
Click to expand...


Yeah I've been thinking that too. If not, I don't get the point of being in the class. Forgetting a few prerequisites is one thing, but if you're taking a PLC class and don't even know how to run a simple process like this one, you probably need to retake the prerequisites or set up some tutoring time with the professor. At least spend some time using the help tools suggested in this post to learn some simple tactics like seal ins. Eventually someone is going to ask you to show an example of programming face to face, and you won't be able to ask us for help. It's not so much the asking for help as it is the lack of *apparent* (based on the last few posts) effort on your part to try and absorb the things people are saying to you.
 
Last edited:
cattiebrie,

2nd post of the same thing and we have helped you on each of them.
sorry, but we won't do your homework for you, you gain nothing that way.
when you get a plc programming job, you must think on your feet and that's when your boss and others will discover if you can do the job or not.

post your work based on our answers and we will offer suggestions.
james
 

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