Silo Simulator

[drosales]

On LogixPro the silo simulation has 3 modes, A, B and C. So far we have just been using one but now we need a different program for each. How do I set each program specific to each mode? I have the programs done already just need to apply them to the specified letter mode.

 

[Lancie1]

Drosales,

For Silo Exercise 3, you need to add the selector switch contacts (using 3 parallel rung branches) to the rung that Starts/Stops the Conveyor Motor, Output O:2/0.

Also, on the Solenoid valve Output rung, you need a XIO contact for Selector Switch Position "C".

That's all. All other rungs may stay exactly the same.

You really do not require a totally different program for each operating mode. Read the instructions carefully. When you fully understand the instructions, you will see the solution. Excerpt from the LogixPro student Exercises:

Exercise #3 -- Selectable Mode of Operation
Alter or re-write your program so that the panel mounted Selector switch can be utilized to select one of 3 different modes of operation. The 3 modes shall operate as follows:

When the selector switch is in position "A", the system shall operate in the "Continuous" mode of operation. This is the mode of operation which was used in Exercise #1.

When the selector switch is in position "B", the system shall operate in the "Manual Restart" mode of operation. This is the mode of operation which was used in Exercise #2.

When the selector switch is in position "C", the system shall operate in the "Fill Bypass" mode of operation. In this mode, the boxes will simply move down the conveyor continuously and bypass the fill operation. As in the other modes, the Start and Stop pushbuttons will control the conveyor motion and the Run Lamp will operate as expected.

 

[Lancie1]

By the way, for a method that eliminates ALL material spills on the floor (impossible to do if you follow the instructions), look in the Downloads here for LogixPro Silo_EX._1.rsl. You need to set the GEQ source B (on rung 4) to somewhere between 70 and 100, depending on the speed of the computer that you are using. 78 works on my computer and allows running the conveyor at full speed with no spills.

http://www.plcs.net/downloads/index.php?&direction=0&order=&directory=Allen_Bradley

 

[drosales]

Thanks a lot! Just needed to take a look at it like you said. adding a few inputs here and there and it works correctly.

 

[drosales]

Ok, now for an extra credit assignment i need to add a 5 second delay after the box is filled before the conveyor sends it away. I also need to have the program complete five boxes then bypass two and continue the process. I'm not sure how to use a timer or counter though. Any help how to set something like this up would help. Thanks again.

 

[Lancie1]

Great! Glad you got it on your own. Here is my version, using 7 rungs.

 

[Lancie1]

To delay 5 seconds, add a new rung with Timer T4:0. Set the Preset Value = 50. Control (trigger) the timer with a XIC contact for O:2/4 Box Full. Now on Rung 0 (or the rung with your Conveyor Motor Output O:2/0, change the O:2/4 contact to be a contact for T4:0/DN. That should do the first part.

EDIT: Yes, that did the job. Now for the second part.

 

[Lancie1]

I now have the second part of the extra credit problem working. My approach (there are others!) is to simulate what the Selector Switch would do if I counted 5 boxes, then turned the switch from "A" to "C" position. This allows the switch to still function as it was designed.

1. Add another rung for a counter C5:1. Control it with the Box Prox Sensor I:1/3. Set the Counter Preset to 7 (5 filled, plus 2 bypassed).

2. Add a GRT (Greater Than) on the Rung 0 branch 3, in PARALLEL with the Selector Switch Position C XIC, with Source A = C5:1.ACC, Source B = 5. This comparison instuction simulates switching to Position "C" after 5 boxes have passed.

3. On Rung 1 (or the rung with the Solenoid Output), add a LEQ right after the Selector Switch Position C XIO contact, with same Sources as above. This inhibits the Solenoid fill after 5 boxes and up to 7 boxes, when the counter is reset.

4. Add a C5:1 Counter RES (Reset) somewhere, triggered by (I:1/3 OFF and C5:1/DN ON).

Work on it and let me know if you have problems.