please help me with my plc project :(

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Apr 2011
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CDO
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i'm an electrical engineering student and our professor asked us to do this project.. my friend asked help from engineers where she's doing her on the job training and she said a different program is used for this one.. i'm guessing its the logic pro x thingy, and not the psim.. i need help with what correct codes i should put in.. here are the instructions:

OPERATION:
o The batch mixing process will run as a continuous operation which may be stopped or started at any time using switches S1 and S2.
o The tank is to be filled with a mixture obtained from the separate fill lines using pumps P1 and P2. A counter will control the quantity of product obtained from Line 1 (P1) while the remainder will come from Line 2 (P2). The tank is to be filled to the point where the Hi-Level sensor goes true.
o When filling is complete, the Full light will turn On. Heater O:1/04 and Mixer O:1/00 will be started allowing the mixture to begin heating. Thermostat I:1/04 is used to control the temperature limit.
o The mixer will continue to run for 4 seconds after the mixture reaches the desired temperature. When the mixer stops, pump P3 will be used to drain the product from the tank. The tank will be drained to the point where the Lo-Level sensor trips.
o Once emptied, the fill, mix, heat process will repeat.
o A second counter will be used to track the number of batches that have been mixed. The batch count will be controllable by adjusting the counter's preset.
o Separate counters will be used to track the quantity of product that has been taken from the 2 individual fill lines.
o Run-time timers will be used to keep track of the accumulated Mixer, and Heater operation times.

and here's what my friend got, she told me that the only problem she has is with the 4 second timer:
http://i6.photobucket.com/albums/y2...8236155_100000212468332_1039795_1607550_n.jpg

if it's all right, please show me a screen shot of the corrections.. :( we are so going bonkers with this one..
 
i need help with what correct codes i should put in.. here are the instructions:

OPERATION:
o The batch mixing process will run as a continuous operation which may be stopped or started at any time using switches S1 and S2.

I think most of the PLCs.net members are OK with this, up to this point. However I have a problem on this next part.

o The tank is to be filled with a mixture obtained from the separate fill lines using pumps P1 and P2. A counter will control the quantity of product obtained from Line 1 (P1) while the remainder will come from Line 2 (P2). The tank is to be filled to the point where the Hi-Level sensor goes true.

There appears to be no mention of how the addition of product from line 1 will be measured so that it can be limited.

o When filling is complete, the Full light will turn On. Heater O:1/04 and Mixer O:1/00 will be started allowing the mixture to begin heating. Thermostat I:1/04 is used to control the temperature limit.
o The mixer will continue to run for 4 seconds after the mixture reaches the desired temperature. When the mixer stops, pump P3 will be used to drain the product from the tank. The tank will be drained to the point where the Lo-Level sensor trips.
o Once emptied, the fill, mix, heat process will repeat.

Again I believe most of the PLCs.net members are OK with this.

o A second counter will be used to track the number of batches that have been mixed. The batch count will be controllable by adjusting the counter's preset.

The counter is easy, but how will the counter's preset be adjusted? Details?

o Separate counters will be used to track the quantity of product that has been taken from the 2 individual fill lines.

This requirement implies that the quantity will be displayed somewhere. Where and how? It also somewhat implies that the volume of line 2 is either measured or deduced from the remaining volume of the mixing tank after line 1's volume has been delivered. More details. Also does this need to be in raw counts or engineering units?

o Run-time timers will be used to keep track of the accumulated Mixer, and Heater operation times.

Again how will this info be available? It's easy to have timers for this purpose, but will there be a HMI? or will the info need to be gleaned by watching the ladder? Also what is the maximum reading needed, and what resolution is needed? Milliseconds, minutes, days?

and here's what my friend got, she told me that the only problem she has is with the 4 second timer:
http://i6.photobucket.com/albums/y23..._1607550_n.jpg

If her project requirements are the same as yours, I believe she has more than just a timer problem.
 
When writing down the PLC code, use a variable name for the physical IO rather than an address (which can't be read without electrical drawings). This will make it possible for us to troubleshoot the code and additionally make it easier for you to think about how the program runs.

I recommend using verbs to lead output names and a descriptive name for the input for what it means in the process. For example, you might use RUN_PUMP_P1 for an output and either S1_PB_PRESSED) or S1_START_PB for the other.
 
i'm an electrical engineering student and our professor asked us to do this project.. my friend asked help from engineers where she's doing her on the job training and she said a different program is used for this one.. i'm guessing its the logic pro x thingy, and not the psim.. i need help with what correct codes i should put in.. here are the instructions
I don't know, what is "the logic pro x thingy, and not the psim".
Fortunately, the assignment looks controller brand-independent.

The assignment is a good example of a simple real life application.
I will also illustrate below, how many things, not mentioned in the process general description, should be considered in the real life.
o The batch mixing process will run as a continuous operation which may be stopped or started at any time using switches S1 and S2.
If it may be stopped, it's not continuous.
The term "continuous" needs clarification.

Also, it's unclear what means "stopped".
Are only the executables (pumps, mixer and/or heater) stopped, while the process status is maintained, or the process will restart from the beginning?
In the latter case, what to do with the existing content of the tank, if any?

OPERATION:
o The tank is to be filled with a mixture obtained from the separate fill lines using pumps P1 and P2. A counter will control the quantity of product obtained from Line 1 (P1) while the remainder will come from Line 2 (P2). The tank is to be filled to the point where the Hi-Level sensor goes true.
Does this mean that P1 measures first, and then, the rest is supplied by P2 until the Hi-level sensor activates?
Or P1 and P2 work simultaneously?
In both cases, what should be done if the Hi-level sensor activates before the P1 count is done?
What if the Hi-level sensor never activates due to hardware error?

Heater O:1/04 and Mixer O:1/00 will be started allowing the mixture to begin heating. Thermostat I:1/04 is used to control the temperature limit.
o The mixer will continue to run for 4 seconds after the mixture reaches the desired temperature.
Should the mixture be reheated/remixed on process restart?
If yes, should this be done only for full tank, or also for partially emptied one?

Once emptied...
Again, what if Lo-level sensor never activates due to hardware error?

o A second counter will be used to track the number of batches that have been mixed. The batch count will be controllable by adjusting the counter's preset.
o Separate counters will be used to track the quantity of product that has been taken from the 2 individual fill lines.
o Run-time timers will be used to keep track of the accumulated Mixer, and Heater operation times.
I don't see such counters/timers in your code.

she told me that the only problem she has is with the 4 second timer
As you can see now, this is not the only problem.

AND NOW, A MILLION DOLLAR QUESTION.
What if the controller restarts (reboots) in the middle of the process?
The answer is, you need a sequential state cycle which maintains its state through the controller restart.
This, in turn, means that the states cannot be coils, because even holding bit coils are typically reset on controller start.

if it's all right...
It's not all right, as you can see now.
Even by size, it cannot do everything you described, not to mention my comments.

please show me a screen shot of the corrections...
We do not do other people's homework here.
You will have to do it yourself. Is not all the learning about this?

P.S. Next time use device names in you code, and apply rung comments.
 
Last edited:

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