Newbie with Simple Sorting Conveyor

[PeterW]

Not read too many responses. I have vast experience of tracking 0n conveyors, a few things.

1. An encoder is always needed, regardless of variable speed or not. With something like this with 4 diverts, I wouldn't dream of NOT using some sort of encoder.

A simple encoder could be a proximity switch monitoring something on a non driven shaft.

2. Search this forum, there have been numerous threads on tracking.

 

[Doug-P]

I'm using the Click C0-01DR-D CPU with battery backup retentive memory.

Given that you have already used seven of the eight available inputs I would strongly recommend that, if possible, you consider adding at least one 8-input module. I would be very uncomfortable having only one spare input to fall back on. What if you someday need to add full line detection for each lane?

This next is somewhat off-topic but, here goes. The Click PLC seems very similar to the DL-105 series. I've used those and found the relay outputs suspect. They work fine when they work but every once in awhile a relay will stick on.

 

[PeterW]

I was on the way out when I posted above, so now I have a bit more time.

A couple of important questions.

1. How big are the packages?
2. What is the distance between divert positions?
3. What is the distance from the point where the destination is coded to the first divert.
4. Can the 'boxes' get stuck, i.e are jams a possibility.

FIFO's can be used for tracking, but if they are used you need to put safeguards to allow for missing objects or objects dropped on.

It maybe that your tracking area could be managed without an encoder and without worrying about the effects of stopping and starting (this has a big effect on tracking).

I notice there is no initial synchronization sensor, without this you cannot have an encoder in any case. The initial synchronization sensor would synchronize your object into the tracking zone, without this the encoder would be useless.

With or without the encoder, I would have 4 tracking zones, this would mean to you 4 FIFO's. The first zone would be from the pushbuttons to the first sensor, the other zones would be between the sensors. (edit, 3 zones as there's only 3 diverts)

When an object is detected at the first sensor, pull the next destination from the FIFO (the oldest), if it is for this destination divert the object and zero down the register holding the destination. If it is not for this destination, do not divert and put the destination into the next FIFO and zero the destination word.

Without seeing the conveyor, size, distances and objects, I cannot say whether its advisable to do it this way or not.

 

[Lancie1]

When an object is detected at the first sensor, pull the next destination from the FIFO (the oldest), if it is for this destination divert the object and zero down the register holding the destination. If it is not for this destination, do not divert and put the destination into the next FIFO and zero the destination word.

Peter, that is exactly what I attempted to do in the last CLICk PLC program Revision 3 that I posted. It should work like you described unless my old brain left out some piece of the puzzle. The Automation Direct Click does not offer a real FIFO instruction, so you have to make your own out of counters and copy instructions.

 

[David1224]

Hey guys,

Sorry I haven't posted back. I finished up a test program last night using methods from the example programs and ran the conveyor for a while this morning. Everything seems to be fine so far, so I'll keep working on a final program.

The example programs have been a huge help and I have learned a lot, so I really appreciate it!

Given that you have already used seven of the eight available inputs I would strongly recommend that, if possible, you consider adding at least one 8-input module.

This is actually only part of the overall system. I've got some spare I/O if needed and could always add another module in the future.

 

[Lancie1]

Everything seems to be fine so far, so I'll keep working on a final program.

Congratulations on a successful program!

Are your box input switches really pushbuttons, or some other type (photoswitches maybe)?

 

[David1224]

Congratulations on a successful program!

Thanks, you were a huge help!

Are your box input switches really pushbuttons, or some other type (photoswitches maybe)?

Yes, just simple pushbuttons for now. Down the road we will add a bar code reader.