help

I have been trying to learn plc basics.I have a couple of G.E.Fanucs.
I can do some basic stuff like make a l.e.d. blink. I got a little side-tracked in my progession around timers. Have not even thought about advanced stuff yet. I do want to learn. I downloaded the original psim. I got the box moving and grain to fill the box and even automaticaly start moving again. The problem is everytime the box moved from out under the silo. I would loose just a little. Eventualy the plant shut down. I know this is simple for many of you. I also know there must be many ways to accomplish the task. I am asking for some of you out there to post your ladder diagram


Thanks

Post yours and I'm sure someone will lead you in the right direction!!

If you want something to practice your GE Fanuc programming skills on, check this:

http://forum.mrplc.com/index.php?&act=Downloads&CODE=02&id=310

To amplify what Martin T. said, you'll find that you get more helpful responses when you ask the question "How can I make this ladder logic do such and such" rather than asking "Please send me the ladder logic to do such and such".

Register as a member and you'll be able to post attachments with your questions.

Steve,

Did you write that simulation software?

Yes, I did.

azg73,

In terms of your problem...

I got the box moving and grain to fill the box and even automaticaly start moving again. The problem is everytime the box moved from out under the silo. I would loose just a little. Eventualy the plant shut down.

I don't have the PSIM program. However, I can see that you have one basic problem...

...you are not capturing as much material as is being delivered.

This is basically loss caused by spillage. The spillage is either caused because you are moving the box too soon... grain is still leaving the silo after the box has moved, or...

...you are filling the box too high and the box starts moving too quickly... the over-fill spills out as the box moves.

Again, I don't have PSIM, but I suspect that your problem is more closely associated with the former issue rather than the latter.

It is probably the case that the chute-gate is high up in the chute. If so, then simply closing the chute-gate does not stop the flow of grain.

Whatever grain is still in the chute will continue to fall to the place where the box is... or at least, where it should be.

You need to "know" how much grain that is. If you were to prevent the box from moving, how much extra grain would you acquire in the box after the chute-gate is closed? After acquiring that grain, what is your fill level? How does that compare to your target level?

If it is more than you expected then you need to close the chute-gate sooner. If less, then you need to close the chute-gate later.

The next question is... how long does it take for the grain to stop falling after you close the chute-gate?

You have to delay moving the box for at least that length of time. If you leave any sooner you will have spillage... your plant will eventually shutdown because of loses.

If your spillage is because the box starts moving too quickly... well, then I guess the program is more sophisticated than I thought.

In that case, you would need to control the acceleration rate of the box motion. This involves "Ramping".

So... does this help?