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i always have problem in"bottle line simulation", which lies in filling the bottle without breaking the next one. could anyone give me a hand?

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Sorry about that - couldn't resist.

You might try taking a look at THIS LINK for a hint.

But the big thing is: YOU SAY YOU ARE STUCK, BUT YOU DON'T SAY WHERE. That's akin to calling AAA for a tow, and not giving them the road you're on. We have to know where you are stuck in order to send the tow truck to the right place to get you out.

From Wen

I received this via PM:

i tried to fill the high bottle first and what i did is when the high bottle arrives to the filling place i let the main conveyor stop and then fill the bottle. i use a timer to count the time of this stop and a counter to force the fill tube fill once and stop until next bottle comes.

in my program i use the status output file "stop the main conveyor" to start the timer. and after the timer is done i need to reset it and let the "stop the main conveyor" false. so if i use the "time is done" to unlatch "stop the main conveyor", it will cause some problem.

i am not sure if you get my point or not. it's difficult to talk about it without seeing the program. maybe tonight i can send you my program for a check if you have free time to see it. anyway, thanks for your reply very much.

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I'm happy to help, but keep several things in mind:

1) It's better if you post to the board, instead of via Private Message, for two reasons: I've been known to make a mistake or two - when that happens, lurkers come out to set us both straight; and some other student may in the future stumble across your post - it will save me (or anyone else from repeatedly repeating ourselves repeatedly.

2) I have NO idea what your task is - I had thought I had recognized it (the link I gave), but that link was to the Simulation v. Reality problem. Yours is different.

3) While I have several software packages for programming PLCs, I don't think I have yours, nor do I have any interest in acquiring/installing it, even "free from the internet". Posting your code will LIMIT the number of responses. Your goal on this forum should be to MAXIMIZE your responses. From what I've seen, The Learning Pit's software simulates RSLogix, and you can use it to generate .GIFs or .JPGs, which you can post here. DON'T POST YOUR ENTIRE PROGRAM!!! Post only the portion that seems to not be working the way you expect. While not all of us can read an .RSS file, ALL of us speak ladder (and many have been known to dream in ladder).

4) Your problem seems to be conceptual, not logical. That is, I'm not convinced that YOU understand what you are trying to accomplish. We have found that once the problem is properly understood, and properly stated, the ladder code practically writes itself. So before posting any code, first describe the system.

What's supposed to happen when. Slow down your thinking, and try to look at the world from the prespective of each peice of equipment, one at a time. Pretend that you are the conveyor. What event(s) cause you to move? What event(s) cause you to stop moving? Don't worry about what the fill valve is doing, just focus on your job (moving and not moving bottles). Once you understand that job, THEN focus on the fill valve. One by one, examine every OUTPUT that the PLC controls, and understand the rules that govern their lives. ONLY THEN do you look at the bigger picture, watching for conflicts.

If you have a sequence, think in terms of Actions and Transitions. You are on step 1. What do you do?(action) When do you stop doing what you are doing and go on to step 2?(transition). Watch the words carefully you use to describe things. "While" and "Until" are do not belong in Actions - they indicate the Transition. It is perfectly OK to do many of the same things on multiple sequential steps.

This should be enough to get you started.

bottle line

i took it for granted that you are familiar with the problem posted on the RSLogix webpage so i didn't explain it before.

actually i am just learning PLC programing by working on the exercises in the Learning Pit's software RSLogix. Bottle line simulation is one of them. what i want to do is just finish the task described in the exercise, which is posted as this:" Energizing the fill tube solenoid O:2/6 will cause the fill tube to extend and enter the positioned bottle. You then must make a choice of discharging a large or small quantity of product into the bottle utilizing the appropriate charge solenoid O:2/7 or O:2/8. Once again, the Boolean data contained in the bit arrays will be used in determining the correct action to be taken."

btw, it seems i cannot put the ladder picture here.