Assignment help !!!!

[blackhenry]

I'm an entry Student for PLC , i got one assignment from the teacher and still stuck for 2 weeks, now i'm begging the professional to help me this project (

Stage1: I have to design a program for an engineering workshop. This workshop has two very large compressors which feed air into a holding tank. On the top of this holding tank is pressure switch. The way this system work is when the tank is empty the pressure switch will close and only the first compressor will star to fill the tank with air. When it is full oc air the pressure switch will open its contact thus stopping the compressor. As the air is being used the pressure switch closes to star the compressor, now being the second one. This process repeats its self five (5) times , then a warning bell must sound for ten (10) seconds to let the operator know he must add oil

Stage 2: A low pressure switch has been added to the tank. When the air stays too lo for 5 minutes, the plc starts both compressors and runs them for 10 minutes and then return to normal duty. This emergency start does not count toward the bell cycle

 

[Steve Bailey]

You have written a pretty good description of what is supposed to happen. All you have to do is translate that description to ladder logic. What have you done so far?

 

[blackhenry]

I'm sorry , I haven't done anything, still thinking about that, can you give me an example ladder plc circuit program to do it, my teacher suggest me use a flip flop, but I have no idea, sorry for noob, please help me

 

[daba]

This is not a site for getting your coursework done for you.

Telling you how to do it will not help you for the future.

Correcting your mistakes, so long as you understand the mistakes you made, is a powerful learning tool.

You can't show what you have done so far, as you said you've done nothing.

The assignment seems to be moderately advanced, and will be based on what you have learned/achieved so far in the course.

Do you really have no idea how to proceed with this assignment...?

 

[blackhenry]

This is what i am doing

This file here what i am doing, did i do a right thing ?

 

[Viks]

Can you zip your .rss file and post it here? It would be easier to look at the actual program than just look at an image to understand your code.

 

[bernie_carlton]

As Viks suggested, to a 'zip' of your RSS file then post it here. Though you won't receive a direct answer for your homework, you will probably receive a better education from the experts here than from any single instructor. Take their advice, follow their suggestions and feedback. In a matter of a few posts you will probably be far ahead in understanding.

 

[Plcwill]

You have written a pretty good description of what is supposed to happen. All you have to do is translate that description to ladder logic. What have you done so far?

As Steve states here. Do you have the description the instructor give to you will be a big help you and the forum members

I did noticed a minor problem with the ladder logic. But in order to give you a better answer, I would need to see the all of the ladder logic.

 

[Manglemender]

My advice would be to start with paper and pencil and draw yourself a flowchart based on the functional description that you gave.

Once you have your flowchart, you can start to translate that into code.

Nick

 

[DamianInRochester]

My advice would be to start with paper and pencil and draw yourself a flowchart based on the functional description that you gave.

Once you have your flowchart, you can start to translate that into code.

Nick

Complete agreement.
This is the time to get in the habbit of doing this.

You should first break down the process into terms that you already understand, even if it is just a sequence list.

Then, it only becomes are matter of translating that from "the terms you understand" to the "terms the PLC understands".

 

[Rube]

I can already tell you from your #1 jpg to rewrite rung #1--it won't give you want you're needing. You're close to what you want this rung to do, just not quite there yet.

Also look through the next two rungs as they relate to rung #1's output bit. Again, close, but... (think bit state-- 1 or 0)

 

[Lancie1]

Henry,

First, it is not a good start when you try to fool us with an old Pump control program. At least change the labels from "Pump" to "Compressor, and the "Level Switches" to "Pressure Switches".

Second, you must decide at what pressures to set the switches. SAFETY CONSIDERATION: Beacuase this is an Engineering Student Workshop, make the maximum pressure low (40 PSI or somewhere around there) so as to be less dangerous to inexpeienced beginners. Label the pressure switches like this:

Pressure Switch 1 (closes at 32 PSI, opens at 40 PSI)
Pressure Switch 2 (closes at 30 PSI, opens at 40 PSI)

EDIT: Sorry for the confusion, Second, your STAGE 1 assignment is to alternate the compressors, first when the Pressure Switch 1 calls for air, run compressor 1 until pressure builds to 40 psi (where compressor will stop if you have used PS1 to start it up at 32 PSI. Then use Alternator Logic to cause Compressor 2 to run the next time that the pressure drops to 32 PSI. Search this site for "Alternator". NOTE: When you first start (0 pressure in the tank), both compressors should run to quickly build up the pressure, but once it reaches 40 PSI the first time, then the next time it drops to 32, only 1 compressor should run. Which one is controlled by the Alternator Logic. A compressor air tank should never be run to 0 pressure, because 0 PSI air is useless, and so is 10 PSI air. Set your minimum pressure at some useful level, depending on what air-operated devices and tools are used in this workshop.

Stage 2: run both compressors if one compressor cannot maintain (keep) the pressure from dropping, or cannot increase the pressure due to more air being used than 1 compressor can produce. What you need is logic that looks at Pressure Switch 2, and starts Compressor 2 at the same time that Compressor 1 is also running. If you set your pressure switches as above, then you will not need anything else to cause Compressor 2 to start when Compressor 1 cannot maintain 32 PSI.

 

[blackhenry]

this is what i have done , can anyone guide to me did i do a right thing ? and how can i do the stage 2 ?
Thank you so much for you guys here

 

[OkiePC]

Your program looks okay so far. At least you have commented your addresses and put in some effort. You do have a couple of mistakes. One of them is the fact that Pump1 must be running before Pump2 can start under any circumstances.

I would encourage you to take a look at a simple state engine type of construction which can make for more organized code. You only have about 4 states for your system but the practice of using state engine type logic pretty much guarantees predictable behavior and can be programmed and followed very easily:

http://www.plctalk.net/qanda/showthread.php?t=52654

 

[blackhenry]

Can you tell me what is the mistake i got on my program? yeah it when press switch both Pump 1&2 running