I need help with programming PLC

I'm newbe with PLC, and now I need some help.
It is about AB Micrologix 1200 and I need some programming tips! Now I have 2 sensors, one is for counting and another is for controlling presence of some adhesive on boxes. Every box without this adhesive should be rejected with delay of five count.
Is it possible?

THX in advance

You don't indicate that you have any outputs to run a reject mechanism. If you can adequately detect boxes without the adhesive, HOW are you going to reject them?

And a five count delay of what? seconds? minutes? boxes? elephants?

The hardest - and first - part of any automation project is to positively define what you want to do. IF you can do that (and you have the physical mechanics to do what you need to do), then yes you can do this.

So-- what exactly do you want to do? Write it out -- either as an outline, or a flow chart, or pseudo-code.

e.g.

IF box_present_sensor THEN increment counter
IF box_present_sensor AND NOT adhesive_detector THEN...

Try this first...

I have an output mechanism, it is a pneumatic valve! And a five count delay of boxes

It sounds like the reject station is five boxes downstream of the adhesive detection? I've seen this sort of thing done with a register shift or a bit-shift.

The speed of product line is from 0 to 120 boxes/min.

So you mean u are looking for the adhesive in the boxes, and if in some one box is missing, reject it with a pneumatic valve that is 5 boxes AFTER the sensig device?

One of the old traditional ways to do this is to use a Bit-Shift Register instruction, such as "BSL" in the RSLogix programs.

Every time the Box Count detector = 1, shift the BSL by 1. Every time the Adhesive Detector = 1, insert a 1 into the BSL. If Bit 6 of the BSL = 1, trigger the Pneumatic Valve output.

Heres a Bit-Shift how to link.

http://www.mrplc.com/kb/index.php?page=index_v2&id=71&c=12

I work for a edible oil company and i did the same the other day and it works perfect.
I have to dicard a box when weight is lower than standard, that means that one bottle was missing in the box due to problems in the packagin machine that only happens once or twice a day and what i did was to use a counter on the weight station i use a photocell and when a bad box is detected that number ( in the counter) is enter into a fifo, later that box passes in front on the reject station i have another photocell and another counter if the number of the box in front of the reject station is included in the fifo list the the box is rejected.
Advantages: it doesn´t matter the space between the weigh station and the the reject station , the size of the fifo must be bigger that the amount of boxes that can be between the two stations.
Disadvantage: no body can put or take boxes beteewn the two stations.
I installed a light indicator to be sure that the counter are synchronized when there are no boxes in between the two stations and if for some reason they are not synced, the same light indicator has a push button that resets the fifo contents and make counter accumulators the same so they are synchronized.
hope this will help

isko, will this help you

I hope this can be of some help
http://www.picvault.info/images/537057396_LadderRungs.jpg

Fishenguy,

It appears that your logic is to turn on a sequence of outputs from O:2/0 to O:2/4. In this case Isko only wants to control ONE output, the pneumatic valve. Also, the "Bit Address" for the BSL in this case must be the Adhesive Detector, not a Reject Button. However, it will probably be necessary for Isko to add a Reset button (or some other method) to reset the BSL after a shutdown or maintenace activities.

Also a "#" must be inserted in the BSL File Address.

File is the address of the bit array you want to shift. You must use the file indicator (#) in the bit array address. You must start the array at a 16-bit element boundary, for example, use bit 0 of element #1, 2, 3, etc.

Rockwell Software 2000

Click to expand...

Lancie, the info I sent came from a plc simulator i have and I didn't have time to edit it. I have to get ready to leave the house right now and wanted to share what I could.

Okay, no problem, and thanks for sharing. Which PLC simulator are you using?

Lancie, The simulator is LogixPro from the Learning Pit. It helps me to look at what I've written, but it does have its limitations.

After all the help everyone's given me, I feel kind of bad about hurrying up an incomplete answer like that. I'll give more thought to my replys from now on. I promise.

widelto said:

I work for a edible oil company and i did the same the other day and it works perfect.
I have to dicard a box when weight is lower than standard, that means that one bottle was missing in the box due to problems in the packagin machine that only happens once or twice a day and what i did was to use a counter on the weight station i use a photocell and when a bad box is detected that number ( in the counter) is enter into a fifo, later that box passes in front on the reject station i have another photocell and another counter if the number of the box in front of the reject station is included in the fifo list the the box is rejected.
Advantages: it doesn´t matter the space between the weigh station and the the reject station , the size of the fifo must be bigger that the amount of boxes that can be between the two stations.
Disadvantage: no body can put or take boxes beteewn the two stations.
I installed a light indicator to be sure that the counter are synchronized when there are no boxes in between the two stations and if for some reason they are not synced, the same light indicator has a push button that resets the fifo contents and make counter accumulators the same so they are synchronized.
hope this will help

Click to expand...

To add to this if the conveyor is a constant speed then boxes should pass the sensors in regular time intervals, you can always add a timer to make sure a box triggers the sensor in a specified time period.

Even if varied speed the timer preset can be changed accordingly.

This could also be used to adjust the FIFO.