Whats the best way

I have the job to put a PLC + PC with 3 touch screens in a industrial Laundry.Basically Operator will load various "Bags" which will go along a conveyor prior to going into 3 washing machines.Depending on whats in the bags will determine the wash cycle outputted to washers.
Any thoughts on how I would go about Tracking all the bags(up to 40 at any one time) and display the process on a PC.The 3 touch screens are for the 3 loading areas.

Many Thanks

Ho Gordo: That is a really big question. You have to know where in the line the 3 grading stations are located, and the flow of the graded bags of laundry. To tackle this you will have to be familiar with shift registers (file copy) and very possibly FIFO and LIFO load and unload instructions. again, it really all depends on where the "graders" are located. To keep track of the 40 bags on the conveyor and send them to their respective washers is pretty easy as long as nothing gets added or taken from the belt between when you start tracking and when you drop them off. You Could use a shift register to track them as you can load information into the files which you need to do (ie: bag type "a" load a 1, bag type "b" load a 2 and bag type "c" load a 3. If you encode the conveyor (put a proximity sensor on the drive sprocket), you can keep track of the bags by shifting the shift register (containing the type 1,2, or 3 bag information)with the encoder prox pulses. then at the drop off end simply look at the shift file to send it to the coresponding washer. your biggest challange is sorting out how the grading is going to take place. hope this helps.....Les

It depends

There's the best way, and then there's the cheapest way. The truth will usually be somewhere in between.

Is the conveyor a closed loop or a point-to-point type?

If a bag's destination washer is full or otherwise unavailable, will the bag recirculate or will it be dropped off somewhere and need to be reinducted?

When the bag reaches its destination, is it removed from the conveyor by hand or automation?

Are all of the load points upstream of all of the washers?

Punch 'automated laundry' or 'laundry automation' into Google and see what you find.

Thanks for the help and your time on this.

The conveyor is a point-to-point type.
If all washers are unavailable the bags will be dropped off...and will manually reinducted.
The bags will automatically be dropped into washers.
Yes the 3 load points are up stream of washers.
Cheers.

Gordo777,

Yes, a shift register is probably your best tracking method for 40 bags. The shift register bits need to be physically tied to the conveyor movement (using an encoder or proximity switch as sugggested by others). Also, my past experiences with tracking objects that have no self-identifying capability (such as a bar code), you will need to establish a minimum distance between bags. If the bags are allowed to be placed on the conveyor end-to-end or as close as possible, then you will have trouble in "picking" any particular bag when it gets to its washer. You need some way to space out the bags to give you a little time to activate a solenoid or gate or pusher to move any individual bag.

Gordo777 said:

The conveyor is a point-to-point type.

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In this case you don't need to deal with recirculating the bags. This makes the program a little easier.

The bags will automatically be dropped into washers.

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Good! No manual intervention once the bag is on its way.

Yes the 3 load points are up stream of washers.

Click to expand...

Here's one option: Find an outfit which produces RFID tags and readers and affix a tag, numbered 1 through 40 to each bag. IMHO, a marking device which stays with the bag and is impervious to water and chemicals would be a good thing.

The operator enters the three pieces of information: tag number; destination; and wash type, and this is forwarded to the PLC.

Since all incoming bags must pass one point on the conveyor, mount a reader somewhere before the first dropoff point. When a bag with a tag passes the reader, drop/inject it, the tag number, into the (word wide) shift register and start tracking it. If no tag, inject zeroes. Somewhere, X number of pulses downstream, choose a shift register stage near the washer as the dropoff point. Whenever this stage detects a number greater than zero, get the tag number and use it as an index to lookup the destination for that tag. When the destination from the lookup matches the one assigned for that stage, the actuator drops the bag into the washer (assuming the washer is available).

Keep a file parallel with the 1-40 bag destination file to store the wash cycle type. That way, when a bag is dropped, the tag number will also point to the correct wash type for the tag in question so it can easily be retrieved and presented to the washer.

There 'ya go. All 'ya gotta do is...