Help! Please. Silo simulator

Hello.
I am a student in Delaware learning to PLC programming and having little difficulty til now. I am working with the Silo Simulator on Logix Pro and cannot figure for how to control the scan speed or motor speed of this simulator only having access to the address of the motor and no access to the scan speed of the program. I am not asking for anyone to do it for me just point me in the right direction. Thanks.

Winker, how are you controlling the motor? Is it closed loop?. It would be helpfull if you could post a pdf printout of your code.

Winker,

We have worked through the LogixPro Silo exercise before. Just search the threads for User Name "promanen", or "silo" or "LogixPro".

dont know how to attach things to a post

Winker,

Are you working on the first Silo Exercise? Note that you do not have to control the conveyor motor speed, but you do have to stop the conveyor motor (Output O:2/0) when the box is in position underneath the silo discharge nozzle.

Exercise #1 -- Continuous Operation

Completely design and de-bug a ladder control circuit which will automatically position and fill the boxes which are continuously sequenced along the conveyor. Ensure that the following details are also met:

• The sequence can be stopped and re-started at any time using the panel mounted Stop and Start switches.
• The RUN light will remain energized as long as the system is operating automatically.
• The RUN light, Conveyor Motor and Solenoid will de-energize whenever the system is halted via the STOP switch.
• The FILL light will be energized while the box is filling.
• The FULL light will energize when the box is full and will remain that way until the box has moved clear of the prox-sensor.

help!!!

My instructor has pulled this one from his own hat. Switch position A = full; B = 2/3 full; C = 1/3 full and must function for all scan speeds. I only see one scan speed and have no idea how to change the speed of the motor or program scan. Lights I can flash at different speeds but this is beating me up. I have the basic program to start and run the simulator but modificatrions of this type are puzzling me.

Winker,

Oh! You want to change scan speeds on the LogixPro program.

1. Download a program. (See the Offline/Online menu directly underneath the "File" menu, top left of screen.
2. Go "Online".
3. Look at the big Scan Speed slider button that pops up on the top right of your "monitor" menu! Understand that real PLCs generally DO NOT have a scan speed control, but this is a Simulator Program, not a PLC.
4. Slide the slider to the right to run fast, to the left to run slow. This not only changes your so-called PLC "scan speed" but it also makes your motors and all machinery run faster or slower (totally unreal, but useful for student training, I suppose).

I looked right at it and it didnt click. Now I feel stupid. Thanks, my bad.

Winker,

The best I can determine, Level Sensor I:1/04 is not analog, but merely a digital Box Full or Box Not Full. Normally you would use this switch to trigger the conveyor motor to restart when the box is Full.

Now your instructor has came up with this off-the-wall stuff to fill the box not only Full (Selector switch Position "A") but 2/3 full and 1/3 full. Those might be doable if you use a timer to start and stop filling. But how to you handle the varying speeds as set by the "Scan" slider control? Ideas, anyone?

I have an idea that will work. You determine how fast the Scan Speed is set, then adjust the Preset Time of your new Fill Timer based on the Scan Speed setting. This allows your program to fill the boxes 1/3 and 2/3 full at all Scan Speeds.

However, because the Scan Speed control has no direct interface with the PLC program, there is no way to directly determine where the Scan Speed is set. There are one or more ways to indirectly determine the Scan Speed setting. Method 1: Add a rung to monitor the internal PLC clock, memory location S2:4. Notice that S2:4 changes slower when the Scan Speed is set to Low, and S2:4 changes rapidly when Scan Speed is set to Fast.

Does this give you some ideas? Work on it awhile, and then let us know if you need more help.

This sim is not intended to allow the use of variable fill of the box. The instructor is either an idiot or the student has miss-understood the assignment.

Randy,

I thought at first it would be impossible, but there IS a way to do what Winker's instructor requested. It involves a timer and a method to determine the Scan Speed setting.

For a small challenge, I am working on the solution now. That will allow me to point Winker in the right direction.

Lancie, what you say may indeed be true, but by the reaction of this student it is an assignment that is above the talents of the class. I figure there probably is a way to do what is asked, but my impression of the instructor is still that he may be an idiot. The silo simulation is tricky enough for most beginners just to be able to do the box fill and conveyor restart without filling the factory with pink stuff. This assignment is above that and probably will not enhance the learning of the class. JUST MHO!

I tried the timer and method moving different presets into the timer according to what switch setting was chosen before reading lancies post. What I got was an unstable fill amount that wasn't consistant and got worse when I adjusted the scan speed.

Randylud is right, my instructor is an idiot with the mind of a genious and feels that if you read the book, you too can be a genius. Logixpro's book and lab book don't give enough information to be able to do half the labs that my instructor has given us but up til now I have been able to figure them out.

I'm gooigt o try Lancie1's suggestion about the plc system timer.

Winker,


I have the program working. Use two counters triggered by S2:4/1. This gives you a reference that is relative to the Scan Speed setting. Use each Counter Done bit for the 67% and 33% Fills to shut off the solenoid and restart the conveyor.

These counters are used in relationship to what other device?... because the bit changes are relative to PLC speed but what is fill level referenced too. In other words I can put two counters in my program but the done bits have to do something.