Compact Logix L33 programming help

[dmayhugh]

I have an Compact Logix L33 communicating with a MT(Metler Toledo) IND131.

I need to writ PLC code for dispensing product. I have a hopper that has the cpacity of 680 lbs of product.

I may need up to 1280 lbs of product. Since the hopper doesn't hold that much weight. Does anyone have sample PLC code to accomplish this.

Here is my thoughts and I am not getting it figured out in the PLC code.

Target weight: 1280 lbs
Hopper Capacity: 680 lbs

Tare scale
Dispense 680 lbs into hopper.
Store 680 lbs
Empty hopper
Subtract 680 from 1280 = 600

Never have done this before and trying to figure out how to do it.

Thank you,

 

[harryting]

You have to tell us what specifically you are having issue with; the interface to the scale, logic to accomplish a certain specific task, or.. everything?!

 

[dmayhugh]

I have communications. I am not sure how to write the logic to complete the task.

I should have explained more in detail.

Here is the extreme that I have found for the weights and capacity of the hopper

Product total 2083 lbs
Hopper Capacity is 650 lbs.

I do not know how to write the logic to make this happen. I believe the sequence is as follows:
1. Compare if the weight is greater than 680 (Hopper Capacity)
2. tare the hopper
3. Dispense Hopper Capacity
4. save dispensed weight.
5. empty hopper
6. subtract dispense weight from Target weight (Total Weight)
7. tare the hopper
8. Dispense Hopper capacity
9. Save the dispensed weight
10. Empty the hopper
11. Subtract dispensed weight from target weight
12. tare hopper
13. finish dispensing product to target weight.

I have filled container to desired weight but in the past they have been able to hold the total weight. Now I am filling a hopper that will not be able to hold the total weight for some of their recipes.

I hope this makes more sense.

 

[dmayhugh]

I would like to make available the code that I am writing. I can not attached the size of the file the PLC code is.

 

[MarkNightingale]

Here is a quick example.

It is an AOI that I use.

Not much time tonight.

Cheers

Mark

 

[Mispeld]

I'm curious about step #3, "dispense hopper capacity." That sounds like the hard part. Is it filling from belt conveyor, screw auger, dump hopper, shovel, etc.?

For the various computation steps listed (e.g., #2 tare hopper, #4 save dispensed weight), you will want to make sure they are done exactly once after each sub-fill. One way to accomplish this is with "one-shot" instructions. Look at the RS-Logix 5000 online help, ONS instruction, or other resources for guidance.

 

[ASF]

I do this all the time, with exactly that hardware.

Your sequence of operation in your first post is bang on. The only thing you have to be especially careful about is working out how to indicate to an operator that you have done your calculation and stored the value, so that they can now empty the hopper ready to load up the next 680lb. And also, how to have the operator tell the PLC that they are done emptying the hopper, and you can pick up again from where you left off.

One other piece of advice - don't assume that the operator will fully empty the hopper. Log your "pre-dump" weight and compare it to your "post-dump" weight - if you put in 680lb and the operator only took out 675, you need to know that that 5lb has already been "counted" and can't be counted again as the first 5lb of your second fill.

 

[ASF]

Also search the forum for "sequencer". You'll need to write a sequence which will ultimately step through your process in exactly the order you've written it out. There are dozens of threads on how to make them - many of them end up turning into heated arguments about who likes what best and where Bubba comes into the picture, but there's at least plenty of information on the subject.
This thread in particular goes into quite a bit of detail into the different ways, and pros and cons of each.